LokiTarget - IgnoreSslErrors to ignore errors from self signed certificates

[snakefoot]

Trying to resolve #76 (Assign IgnoreSslErrors = true but not recommended in production environment).

Replaced net462 with net471 to provide support for all targetplatforms. Removed net6 + net7 since out of support.

[codecov]

Codecov Report

❌ Patch coverage is 76.47059% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.42%. Comparing base (93f6204) to head (aad9162).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
src/NLog.Loki/LokiTarget.cs	76.47%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #157      +/-   ##
==========================================
- Coverage   79.19%   76.42%   -2.78%     
==========================================
  Files          12       12              
  Lines         399      403       +4     
  Branches       56       57       +1     
==========================================
- Hits          316      308       -8     
- Misses         59       69      +10     
- Partials       24       26       +2     

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