The previous color no longer matches the Java branding colors and hasn't aged well. This matches the newer branding

https://www.color-hex.com/color/2a6277

Checklist:

• I am associating a language with a new file extension.

  • The new extension is used in hundreds of repositories on GitHub.com
    • Search results for each extension:
      • https://github.com/search?utf8=%E2%9C%93&type=Code&ref=searchresults&q=extension%3AFOOBAR+KEYWORDS+NOT+nothack
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • [URL to each sample source, if applicable]
    • Sample license(s):
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

• I am adding a new language.

  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • https://github.com/search?utf8=%E2%9C%93&type=Code&ref=searchresults&q=extension%3AFOOBAR+KEYWORDS+NOT+nothack
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • [URL to each sample source, if applicable]
    • Sample license(s):
  • I have included a syntax highlighting grammar: https://github-lightshow.herokuapp.com/
  • I have updated the heuristics to distinguish my language from others using the same extension.

• I am fixing a misclassified language

  • I have included a new sample for the misclassified language:
    • Sample source(s):
      • [URL to each sample source, if applicable]
    • Sample license(s):
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

• I am changing the source of a syntax highlighting grammar

  • Old: https://github-lightshow.herokuapp.com/
  • New: https://github-lightshow.herokuapp.com/

• I am updating a grammar submodule

• I am adding new or changing current functionality

  • I have added or updated the tests for the new or changed functionality.

• I am changing the color associated with a language

  • I have obtained agreement from the wider language community on this color change.
    • I don't know necessarily where to create a wider discussion but happy to post somewhere you recommend!
    • https://twitter.com/java