Migrate to ESM (#484)

* Migrate to ESM

* just use `require.resolve`

* reuse setup action

* checkout PR head for a sec

* ls things

* try a thing

* the dirname had a trailing whitespace, lol

scripts/bump.ts

@@ -0,0 +1,18 @@
+import { exec } from "@actions/exec";
+import fs from "node:fs";
+import path from "node:path";
+import pkgJson from "../package.json" with { type: "json" };
+
+process.chdir(path.join(import.meta.dirname, ".."));
+
+await exec("changeset", ["version"]);
+
+const releaseLine = `v${pkgJson.version.split(".")[0]}`;
+
+const readmePath = path.join(import.meta.dirname, "..", "README.md");
+const content = fs.readFileSync(readmePath, "utf8");
+const updatedContent = content.replace(
+  /changesets\/action@[^\s]+/g,
+  `changesets/action@${releaseLine}`
+);
+fs.writeFileSync(readmePath, updatedContent);