build: render the tap formula against any tag pin

The tap job matched the literal v0.1.0 url line, so bumping the pin
broke the release render. The pin is now matched generically and
marked in-source as a placeholder the workflow rewrites; the tap
always ships the release tarball with its real sha256.

.github/workflows/release.yml

@@ -132,8 +132,7 @@ jobs:
           sha="$(cut -d' ' -f1 "dist/ecrou-v$v-darwin-arm64.tar.gz.sha256")"
           url="https://github.com/vhaudiquet/ecrou/archive/refs/tags/v$v.tar.gz"
           mkdir -p formula/Formula
-          sed -e 's|^  # Pinned by tag until the first release exists; switch to the$|  # Published by the ecrou release workflow; do not edit by hand.|'               -e '/^  # release tarball + sha256 then\.$/d'               -e "s|^  url \"https://github.com/vhaudiquet/ecrou.git\", tag: \"v0.1.0\"$|  url \"$url\"\n  sha256 \"$sha\"|" \
-            packaging/homebrew/Formula/ecrou.rb > formula/Formula/ecrou.rb
+          sed -e '/^  # Placeholder pin:/d' -e "s|^  url \"https://github.com/vhaudiquet/ecrou.git\", tag: \"v[0-9][0-9.]*\"$|  url \"$url\"\n  sha256 \"$sha\"|" packaging/homebrew/Formula/ecrou.rb > formula/Formula/ecrou.rb
           grep -q "sha256 \"$sha\"" formula/Formula/ecrou.rb
           git clone -q "https://x-access-token:$TAP_TOKEN@github.com/vhaudiquet/homebrew-ecrou" tap
           cp formula/Formula/ecrou.rb tap/Formula/ecrou.rb

packaging/homebrew/Formula/ecrou.rb

@@ -5,8 +5,7 @@
 class Ecrou < Formula
   desc "a small microVM runtime based on libkrun"
   homepage "https://github.com/vhaudiquet/ecrou"
-  # Pinned by tag until the first release exists; switch to the
-  # release tarball + sha256 then.
+  # Placeholder pin: the release workflow rewrites url and sha256 on publish.
   url "https://github.com/vhaudiquet/ecrou.git", tag: "v0.1.0"
   license "MIT"