Support deployment via Helm to kube 1.19 clusters

[xairos]

First, thank you for the Sloth project! This kind of tool is sorely needed to take much of the toil out of generating SLO-based metrics, visualizations, and alerts 😀

We want to use the Helm deploy method and would love to stay in sync with upstream, but are running a 1.19 cluster at the moment.

score-sloth                       sloth                              False   Helm install failed: chart requires kubeVersion: >= 1.20.0 which is incompatible with Kubernetes v1.19.12-gke.2101   17h

This change would relax the chart's version restriction by a minor kube version. It seemed like this wouldn't be problematic, since CI already tests against kube 1.19?

sloth/.github/workflows/ci.yaml

Lines 69 to 71 in 3f0d37f

	strategy:
	matrix:
	kubernetes: [1.19.11, 1.20.7, 1.21.1, 1.22.0]

[slok]

Hey @xairos, Thanks for the PR! it makes sense :)

[codecov-commenter]

Codecov Report

Merging #161 (ca41c8c) into main (3f0d37f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #161   +/-   ##
=======================================
  Coverage   78.10%   78.10%           
=======================================
  Files          16       16           
  Lines        1311     1311           
=======================================
  Hits         1024     1024           
  Misses        233      233           
  Partials       54       54           

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[slok]

@xairos the Helm tests are failing, could you fix them, please 😄 ?

Here are the expected outputs that don't match: https://github.com/slok/sloth/tree/main/deploy/kubernetes/helm/tests/testdata/output

[slok]

Awesome! Many thanks!

[xairos]

Fantastic, thank you!