Fix the return type of `Enumerable#sum` for union elements #5695

	name: Regex Engine CI

	on: [push, pull_request]

	permissions: {}

	concurrency:
	group: ${{ github.workflow }}-${{ github.ref }}
	cancel-in-progress: ${{ github.ref != 'refs/heads/master' }}

	jobs:
	pcre:
	runs-on: ubuntu-latest
	name: "PCRE"
	container: crystallang/crystal:1.14.0-alpine
	steps:
	- name: Download Crystal source
	uses: actions/checkout@v4
	- name: Remove PCRE2
	run: apk del pcre2-dev
	- name: Assert using PCRE
	run: bin/crystal eval 'abort unless Regex::Engine == Regex::PCRE'
	- name: Show PCRE config
	run: bin/crystal scripts/print_regex_config.cr
	- name: Run Regex specs
	run: bin/crystal spec --order=random spec/std/regex*
	pcre2:
	runs-on: ubuntu-latest
	name: "PCRE2"
	container: crystallang/crystal:1.14.0-alpine
	steps:
	- name: Download Crystal source
	uses: actions/checkout@v4
	- name: Assert using PCRE2
	run: bin/crystal eval 'abort unless Regex::Engine == Regex::PCRE2'
	- name: Assert select PCRE
	run: bin/crystal eval -Duse_pcre 'abort unless Regex::Engine == Regex::PCRE'
	- name: Show PCRE2 config
	run: bin/crystal scripts/print_regex_config.cr
	- name: Run Regex specs
	run: bin/crystal spec --order=random spec/std/regex*

Provide feedback