Upgrade Typscript to v2.8.3

[d3r3kk]

Fixes #1604

This pull request:

• Has a title summarizes what is changing
• Includes a news entry file (remember to thank yourself!)
• Has unit tests & code coverage is not adversely affected (within reason)
• Works on all actively maintained versions of Python (e.g. Python 2.7 & the latest Python 3 release)
• Works on Windows 10, macOS, and Linux (e.g. considered file system case-sensitivity)

[codecov]

Codecov Report

Merging #1686 into master will increase coverage by 0.13%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1686      +/-   ##
==========================================
+ Coverage   71.38%   71.51%   +0.13%     
==========================================
  Files         277      277              
  Lines       13014    13014              
  Branches     2344     2344              
==========================================
+ Hits         9290     9307      +17     
+ Misses       3583     3570      -13     
+ Partials      141      137       -4

Impacted Files	Coverage Δ
...rc/client/debugger/PythonProcessCallbackHandler.ts	52.96% <0%> (-1.32%)	⬇️
src/client/linters/lintingEngine.ts	91.22% <0%> (+0.87%)	⬆️
src/client/debugger/mainV2.ts	77.82% <0%> (+2.82%)	⬆️
src/client/debugger/PythonProcess.ts	51.25% <0%> (+5.41%)	⬆️

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