Use chg in GitHub Actions tests (#355)

Should speed testing up by a minute or two.

Author: rmunn

.github/workflows/dotnet-build.yml

@@ -74,6 +74,7 @@ jobs:
           source environ
           dotnet test -l:"console;verbosity=normal" -l:nunit -c Release
         env:
+          CHORUS_HG_EXE: chg
           BUILD_NUMBER: ${{ github.run_number }}
           DbVersion: ${{ matrix.dbversion }}
           VSTEST_TESTHOST_SHUTDOWN_TIMEOUT: "30000"