ci: simplify build-gems workflow after rb-sys 0.9.124 bump

Author: kateinoigakukun

.github/workflows/build-gems.yml

@@ -54,13 +54,6 @@ jobs:
             echo "Failed to detect rb-sys version from Cargo.lock" >&2
             exit 1
           fi
-
-          # Ruby 4.0 cross-compilation support requires newer rb-sys/rake-compiler-dock.
-          min_version="0.9.124"
-          if [ "$(printf '%s\n' "$version" "$min_version" | sort -V | tail -n1)" != "$version" ]; then
-            version="$min_version"
-          fi
-
           echo "version=$version" >> "$GITHUB_OUTPUT"
 
       - name: Build native gem with rb-sys-dock
@@ -71,10 +64,7 @@ jobs:
           RB_SYS_VERSION: ${{ steps.rb-sys.outputs.version }}
         run: |
           gem install rb_sys -v "$RB_SYS_VERSION"
-          # rb-sys gem and docker image tags are released independently.
-          # Use the latest image tag currently published for all platforms.
-          RCD_IMAGE_VERSION="0.9.124" \
-            rb-sys-dock --platform "$PLATFORM" --directory . --ruby-versions "$RUBY_VERSIONS" --build
+          rb-sys-dock --platform "$PLATFORM" --directory . --ruby-versions "$RUBY_VERSIONS" --build
 
           gem_path="$(find ./pkg -name "*-${PLATFORM}.gem" | head -n1)"
           if [ -z "$gem_path" ]; then