feat(testing): updated ensure-zookeeper-env.sh to match minimum version of zk

[ThosRTanner]

These changes allow people to build locally with a reasonable chance of success making PRs a bit less likely to fail.

Also updated .gitignore to cover a few local files when developing with visual studio

Why is this needed?

• Building kazoo locally would fail because the ZOOKEEPER_VERSION env variable isn't exported
• The currently selected default version was way short of the minimum supported version, resulting in odd failures when building locally, and odd failures in PR builds
• Also added some stuff to .gitignore to assist in local builds with visual studio code

Proposed Changes

• Move all optional settings into ensure-zookeeper-env.sh out of workflows/testing.yml
• Change ensure-zookeeper-env.sh so if ZOOKEEPER_VERSION wasn't supplied, to select the lowest (at the time of writing) supported version of zookeeper and export the variable
• Updated .gitignore to include .*_cache and venv* as this makes them greyed out in visual studio code

Does this PR introduce any breaking change?

No

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.70%. Comparing base (86e69f2) to head (a429e4f).
⚠️ Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #776      +/-   ##
==========================================
+ Coverage   96.67%   96.70%   +0.02%     
==========================================
  Files          27       27              
  Lines        3553     3554       +1     
==========================================
+ Hits         3435     3437       +2     
+ Misses        118      117       -1     

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[StephenSorriaux]

Thank you for taking care of my old TODO.

[ThosRTanner]

Thank you for taking care of my old TODO.
No probs. I think you need to re-review it after I merged it but at least it's not complaining about coverage now!

[StephenSorriaux]

Can you please amend your commit and match the contribution guideline? Just adding feat(testing): before the current message would be enough. That helps when we auto generate the changelog for a release.

[ThosRTanner]

@StephenSorriaux oops - hope that worked. it dismissed your review again...

[StephenSorriaux]

Thanks a lot!