SHA-1 signatures will no longer be trusted by default

[mregen]

Proposed changes

• Since some distributions stop to trust SHA1 signatures by default, replace some internal algorithm checks with SHA256 versions.
• The test case to force signature check also reenables ECC tests for .NET 4.8 which had been previously disabled.

Related Issues

• Fixes SHA-1 signatures will no longer be trusted by default #2405

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (9138bb9) 53.60% compared to head (d187213) 54.89%.
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2406      +/-   ##
==========================================
+ Coverage   53.60%   54.89%   +1.28%     
==========================================
  Files         331      331              
  Lines       63866    67207    +3341     
  Branches    13116    13927     +811     
==========================================
+ Hits        34237    36891    +2654     
- Misses      25906    26435     +529     
- Partials     3723     3881     +158     

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[salihgoncu]

All looks fine. Just could not really understand why the ECDSA tests needed to be touched. - Those seem to be part of a different topic.