Revert "Remove post-release step"

This reverts commit d285916451.

.github/workflows/goreleaser.yml

@@ -19,19 +19,6 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GH_PAT_TOKEN }}
           WITH_V: true
           DEFAULT_BUMP: patch
-      - name: Update default.nix
-        uses: MathieuSoysal/file-updater-for-release@v1.0.3
-        with:
-          files: default.nix # List of files to update
-          prefix: "version = \"" # Prefix before the version, default is: ""
-          with-checkout: false # If you don't want to checkout the repo, default is: true
-      - name: Push changes
-        uses: EndBug/add-and-commit@v9
-        with:
-          committer_name: GitHub Actions
-          committer_email: actions@github.com
-          add: default.nix
-          message: 'Update default.nix with latest version number'
       - name: Set up Go
         uses: actions/setup-go@v2
         with:

.github/workflows/post-release.yml

@@ -0,0 +1,31 @@
+name: Update default.nix with latest version
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+          token: ${{ secrets.GH_PAT_TOKEN }} # Needs write access to the repo
+          ref: master 
+      - name: Update default.nix
+        uses: MathieuSoysal/file-updater-for-release@v1.0.3
+        with:
+          files: default.nix # List of files to update
+          prefix: "version = \"" # Prefix before the version, default is: ""
+          with-checkout: false # If you don't want to checkout the repo, default is: true
+
+      - name: Push changes
+        uses: EndBug/add-and-commit@v9
+        with:
+          committer_name: GitHub Actions
+          committer_email: actions@github.com
+          add: default.nix
+          message: 'Update default.nix with latest version number'
+