List full platform names in release notes

[dduugg]

Problem

The "Supported Platforms" list that CD writes into each GitHub release is garbled. v2.2.0's read:

- musl
- linux
- ucrt
- darwin
- darwin
- musl
- linux

The sed kept only the text after the last hyphen in each gem filename, so aarch64-linux-musl became musl. The grep -E '\-(x86|arm|aarch)' filter also dropped x64-mingw-ucrt. v2.2.0's notes have been corrected by hand; this fixes the workflow for future releases.

Change

Build the list by stripping the known code_ownership-<version>- prefix and .gem suffix from each platform gem. The source gem doesn't match the glob, so it's excluded without a filter.

Verification

The "Create GitHub Release" step can't run in a dry run, so I extracted its run script from cd.yml and ran it locally against v2.2.0's nine asset filenames, with gh stubbed out:

• On main, it reproduces the garbled list above exactly.
• On this branch, it lists all eight platforms by full name: aarch64-linux-musl, aarch64-linux, aarch64-mingw-ucrt, arm64-darwin, x64-mingw-ucrt, x86_64-darwin, x86_64-linux-musl, x86_64-linux.
• A prerelease version (2.3.0.pre.1) and a source-gem-only pkg/ both come out right. The latter gives an empty list rather than - *.

actionlint's findings are unchanged except for one removed: the ls | grep warning (SC2010).

• I bumped the gem version (or don't need to) 💎