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

.github/actions/ci-setup/action.yml

@@ -0,0 +1,14 @@
+name: Setup CI
+
+runs:
+  using: composite
+  steps:
+    - name: Setup Node.js
+      uses: actions/setup-node@v4
+      with:
+        node-version-file: ".node-version"
+        cache: yarn
+
+    - name: Install dependencies
+      shell: bash
+      run: yarn install --frozen-lockfile

.github/workflows/ci.yml

@@ -13,16 +13,11 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - name: Checkout Repo
-        uses: actions/checkout@v4
-
-      - name: Use Node.js 20
-        uses: actions/setup-node@v4
+      - uses: actions/checkout@v4
         with:
-          node-version: 20.x
+          ref: ${{ github.event.pull_request.head.sha }}
 
-      - name: Install Dependencies
-        run: yarn --frozen-lockfile
+      - uses: ./.github/actions/ci-setup
 
       - name: Typecheck
         run: yarn typecheck

.github/workflows/release-pr.yml

@@ -37,6 +37,7 @@ jobs:
     needs: release_check
     steps:
       - uses: actions/checkout@v4
+      - uses: ./.github/actions/ci-setup
 
       - name: Checkout pull request
         run: gh pr checkout ${{ github.event.issue.number }}
@@ -54,14 +55,6 @@ jobs:
         if: steps.check_version_packages.outputs.version_packages == 'true'
         run: git reset --hard HEAD~1
 
-      - name: Use Node.js 20
-        uses: actions/setup-node@v4
-        with:
-          node-version: 20.x
-
-      - name: Install Dependencies
-        run: yarn --frozen-lockfile
-
       - run: yarn changeset version --snapshot pr${{ github.event.issue.number }}
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/version-or-publish.yml

@@ -11,16 +11,8 @@ jobs:
   changesets:
     runs-on: ubuntu-latest
     steps:
-      - name: Checkout Repo
-        uses: actions/checkout@v4
-
-      - name: Use Node.js 20
-        uses: actions/setup-node@v4
-        with:
-          node-version: 20.x
-
-      - name: Install Dependencies
-        run: yarn --frozen-lockfile
+      - uses: actions/checkout@v4
+      - uses: ./.github/actions/ci-setup
 
       - name: Build
         run: yarn build