Mark parser.c and Parser.java as generated files

This way they're hidden in diffs.

However so ensure no code is slipped into it, we ensure on CI
that what was committed is really the Ragel output.

Author: byroot

.gitattributes

@@ -0,0 +1,2 @@
+ext/json/ext/parser/parser.c linguist-generated=true
+java/src/json/ext/Parser.java linguist-generated=true

.github/workflows/ci.yml

@@ -48,7 +48,16 @@ jobs:
           bundle config --without benchmark
           bundle install
 
-      - run: rake compile
+      - run: rake ragel compile
+
+      - run: |
+          if ! git diff-index --quiet HEAD; then
+              printf 'These files changed when running Ragel:\n\n'
+              git diff-index HEAD
+              echo ---------
+              git diff
+              exit 1
+          fi
 
       - run: rake test JSON_COMPACT=1