Add PHPUnit problem matcher

src/matchers.ts

@@ -0,0 +1,10 @@
+import * as path from 'path';
+
+/**
+ * Add matches using the Actions Toolkit problem matchers syntax
+ * https://github.com/actions/toolkit/blob/master/docs/problem-matchers.md
+ */
+export function addMatchers(): void {
+  const matchersPath = path.join(__dirname, '..', '.github/matchers');
+  console.log(`##[add-matcher]${path.join(matchersPath, 'phpunit.json')}`);
+}