fix(network manager networks): make python code verson agnostic

[alxwr]

PR progress checklist (to be filled in by reviewers)

• Changes to documentation are appropriate (or tick if not required)
• Changes to tests are appropriate (or tick if not required)
• Reviews completed

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What type of PR is this?

Primary type

• [build] Changes related to the build system
• [chore] Changes to the build process or auxiliary tools and libraries such as documentation generation
• [ci] Changes to the continuous integration configuration
• [feat] A new feature
• [fix] A bug fix
• [perf] A code change that improves performance
• [refactor] A code change that neither fixes a bug nor adds a feature
• [revert] A change used to revert a previous commit
• [style] Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc.)

Secondary type

• [docs] Documentation changes
• [test] Adding missing or correcting existing tests

Does this PR introduce a BREAKING CHANGE?

No.

Related issues and/or pull requests

–

Describe the changes you're proposing

Support Python 3 in the connection.jinja template.

Pillar / config required to test the proposed changes

–

Debug log showing how the proposed changes work

----------                                                                                                                                 
          ID: /etc/NetworkManager/system-connections/server_udp                                                                              
    Function: file.managed                                                                                                                 
      Result: True                                                                                                                         
     Comment: File /etc/NetworkManager/system-connections/server_udp updated                                                                 
     Started: 18:19:17.635143                                                                                                              
    Duration: 508.104 ms                                                                                                                   
     Changes:                                                                                                                              
              ----------                                                                                                                   
              diff:                                                                                                                        
                  New file
----------
          ID: network_manager_connection_reload
    Function: cmd.run
        Name: /usr/bin/nmcli connection reload
      Result: True
     Comment: Command "/usr/bin/nmcli connection reload" run
     Started: 18:19:26.420264
    Duration: 51.624 ms
     Changes:   
              ----------
              pid:
                  2271118
              retcode:
                  0
              stderr:
              stdout:

Documentation checklist

• Updated the README (e.g. Available states).
• Updated pillar.example.

Testing checklist

• Included in Kitchen (i.e. under state_top).
• Covered by new/existing tests (e.g. InSpec, Serverspec, etc.).
• Updated the relevant test pillar.

Additional context