Update Extra Source Files to include Test Haskell Source files.

Author: drsooch

plugins/hls-alternate-number-format-plugin/hls-alternate-number-format-plugin.cabal

@@ -14,6 +14,8 @@ build-type:         Simple
 extra-source-files:
   LICENSE
   README.md
+  test/testdata/*.hs
+  test/testdata/*.yaml
 
 library
   exposed-modules:  Ide.Plugin.AlternateNumberFormat, Ide.Plugin.Conversion