Add cleanFlexgetVersion to process semver strings

[shawnphoffman]

Motivation for changes:

Fix #182 and try to prevent it from happening again without adding complexity to the server repo.

Detailed changes:

Given the complexity flexget currently has in their server versioning, I added a utility that attempts to parse the semver version and clean it up according to the flexget logic. I added tests to help demonstrate some of the edge cases.

• Handle incomplete semver 3.9 to 3.9.0
• Handle existing logic 1.2.3.dev to 1.2.3-dev.0
• Handle other minor use cases.

Originally, I was going to use the coerce function built into semver to handle the 3.9 to 3.9.0 but that removes prerelease tags and they appear to be useful according to tests.

Addressed issues:

• Fixes Version 3.9 release causes web ui to render blank due to Semver check failing #182

[codecov]

Codecov Report

Merging #183 (8acf7e4) into develop (ecd9c49) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##           develop     #183    +/-   ##
=========================================
  Coverage    90.70%   90.71%            
=========================================
  Files          128      128            
  Lines         2743     2745     +2     
  Branches       330      441   +111     
=========================================
+ Hits          2488     2490     +2     
  Misses         251      251            
  Partials         4        4            

Files Changed	Coverage Δ
src/core/layout/SideNav/Version.tsx	100.00% <100.00%> (ø)

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[gazpachoking]

Excellent, thanks!