Fix TypeError on Python <3.10: add from __future__ import annotations

dict[str, Any] and X | Y union syntax require Python 3.10+. Containers
running centos7/ubuntu20/rocky9 base images ship Python 3.6-3.9 and
crashed on import. Adding the __future__ import makes all annotations
lazy strings, compatible back to Python 3.7.

Affected: templates/decnet_logging.py (+ all 22 template copies),
decnet/logging/syslog_formatter.py, decnet/logging/file_handler.py

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/docker_api/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/elasticsearch/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/ftp/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/http/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/imap/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/k8s/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/ldap/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/llmnr/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/mongodb/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/mqtt/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/mssql/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/mysql/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/pop3/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/postgres/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/rdp/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/redis/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/sip/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/smb/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/smtp/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/snmp/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/tftp/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.
 

templates/vnc/decnet_logging.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+from __future__ import annotations
 """
 Shared RFC 5424 syslog helper for DECNET service templates.