Add render test with user settings

[chris-crone]

- What I did

Added a render test for func Render(app *types.App, env map[string]string) (*composetypes.Config, error) with user settings.

- How to verify it

Run go test ./render

- Description for the changelog

N/A

[silvin-lubecki]

LGTM

[codecov]

Codecov Report

Merging #372 into master will decrease coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master     #372     +/-   ##
=========================================
- Coverage   56.61%   56.51%   -0.1%     
=========================================
  Files          55       55             
  Lines        3031     3031             
=========================================
- Hits         1716     1713      -3     
- Misses       1063     1065      +2     
- Partials      252      253      +1

Impacted Files	Coverage Δ
types/settings/settings.go	92.06% <0%> (-4.77%)	⬇️

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