Build on JDK 8, 11, 14

[dblock]

Signed-off-by: dblock dblock@dblock.org

Description

Added CI for JDK 8, 11 and 14.

Issues Resolved

Closes #66.

Check List

• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[reta]

@dblock same for JDK-17, we need Gradle 7 but Welcome to Gradle 6.7.1! :-)

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (main@229a84a). Click here to learn what that means.
The diff coverage is n/a.

❗ Current head 18949ec differs from pull request most recent head 2830c7f. Consider uploading reports for the commit 2830c7f to get more accurate results

@@           Coverage Diff           @@
##             main     #104   +/-   ##
=======================================
  Coverage        ?   83.77%           
  Complexity      ?      558           
=======================================
  Files           ?       61           
  Lines           ?     2058           
  Branches        ?      146           
=======================================
  Hits            ?     1724           
  Misses          ?      230           
  Partials        ?      104           

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[Bukhtawar]

Thanks @dblock for picking this up