chore: move phpmd.xml file to unify with phpunit-constraint-xmlmatchesxsd (#26)

Author: keradus

.gitattributes

@@ -1,5 +1,4 @@
 /dev-tools/         export-ignore
 /tests/             export-ignore
 /.*                 export-ignore
-/phpmd.xml          export-ignore
 /phpunit.xml.dist   export-ignore

.github/workflows/ci.yaml

@@ -19,7 +19,7 @@ jobs:
       - run: composer validate --strict
       - run: composer normalize --working-dir=dev-tools ../composer.json --dry-run
       - run: dev-tools/vendor/bin/composer-require-checker check composer.json --config-file=.composer-require-checker.json
-      - run: dev-tools/vendor/bin/phpmd src,tests text phpmd.xml
+      - run: dev-tools/vendor/bin/phpmd src,tests text dev-tools/phpmd.xml
       - run: dev-tools/vendor/bin/php-cs-fixer fix --diff --dry-run -v
 
   test: