Convert action to TypeScript

rollup.config.ts

@@ -0,0 +1,22 @@
+// See: https://rollupjs.org/introduction/
+
+import commonjs from '@rollup/plugin-commonjs'
+import nodeResolve from '@rollup/plugin-node-resolve'
+import typescript from '@rollup/plugin-typescript'
+
+const config = {
+  input: 'src/index.ts',
+  output: {
+    esModule: true,
+    file: 'dist/index.js',
+    format: 'es',
+    sourcemap: true
+  },
+  plugins: [
+    typescript({ sourceMap: true }),
+    nodeResolve({ preferBuiltins: true }),
+    commonjs()
+  ]
+}
+
+export default config