Solves 494: added destructor to ssm connection plugin

changelogs/fragments/542-ensure-ssm-plugin-terminates-connections.yml

@@ -0,0 +1,2 @@
+bug_fixes:
+  - aws_ssm - Adds destructor to SSM connection plugin to ensure connections are properly cleaned up after usage (https://github.com/ansible-collections/community.aws/pull/542).

plugins/connection/aws_ssm.py

@@ -280,6 +280,9 @@ def __init__(self, *args, **kwargs):
             self._shell_type = 'powershell'
             self.is_windows = True
 
+    def __del__(self):
+        self.close()
+
     def _connect(self):
         ''' connect to the host via ssm '''