Fix CI bug when PRs delete files

`full-test-ci` receives a list of modified (including deleted) files,
but eslint complains when it tries to lint a nonexistent file.
Fortunately, it has a flag to ignore missing files which we can
just use here.

package.json

@@ -42,7 +42,7 @@
     "test": "mocha",
     "posttest": "npm run tsc",
     "full-test": "npm run lint && npm run tsc && mocha --timeout 8000 --forbid-only -g \".*\"",
-    "full-test-ci": "eslint ${FILES} --max-warnings 0 && npm run tsc && (([ \"$SKIPSIMTESTS\" = true ] && mocha --timeout 8000 --forbid-only -g \".*\" --exclude \"test/{sim,random-battles}/**\") || mocha --timeout 8000 --forbid-only -g \".*\")",
+    "full-test-ci": "eslint --no-error-on-unmatched-pattern ${FILES} --max-warnings 0 && npm run tsc && (([ \"$SKIPSIMTESTS\" = true ] && mocha --timeout 8000 --forbid-only -g \".*\" --exclude \"test/{sim,random-battles}/**\") || mocha --timeout 8000 --forbid-only -g \".*\")",
     "postinstall": "npm run build postinstall"
   },
   "bin": "./pokemon-showdown",