ci: stop requiring a linked issue on PRs

The PR check now only asks for the How it was verified section. Linking an
issue with Closes #<n> stays recommended when a PR resolves one.

.github/pull_request_template.md

@@ -1,4 +1,4 @@
-Closes #
+<!-- If this resolves an issue: Closes #<n> -->
 
 ## What and why
 

.github/workflows/pr-check.yml

@@ -24,18 +24,9 @@ jobs:
             const pr = context.payload.pull_request;
             const LABEL = 'needs-info';
             const MARKER = '<!-- pr-check -->';
-            // Docs, CI and pure refactors may skip the linked issue.
-            const NO_ISSUE_TYPES = /^(docs|ci|build|chore|refactor|style|test)(\(.+\))?!?:/;
-
             const body = (pr.body || '').replace(/<!--[\s\S]*?-->/g, '');
             const problems = [];
 
-            const linksIssue =
-              /\b(close[sd]?|fix(e[sd])?|resolve[sd]?)\s*:?\s+(#\d+|https:\/\/github\.com\/[\w.-]+\/[\w.-]+\/issues\/\d+)/i.test(body);
-            if (!linksIssue && !NO_ISSUE_TYPES.test(pr.title)) {
-              problems.push('Link the issue this PR resolves, e.g. `Closes #123`.');
-            }
-
             const verified = body.match(/^##+\s*How it was verified\s*$([\s\S]*?)(?=^##+\s|(?![\s\S]))/im);
             if (!verified || !verified[1].trim()) {
               problems.push('Fill in **How it was verified**: the commands you ran and their results. UI changes need before/after screenshots.');