Fix PR number detection in existing change entries (#83)

The `update` command will filter out any commits that are the result of
PRs that have been referenced already in the changelog.

Unfortunately this PR number detection only looked at the beginning of
the entry. This was because prior to #66, that's where it would be by
default (though this was always a poor decision, because it was always
possible to update the change entry and reference the PR anywhere).
This is especially broken since #66.

We now look for things that look like PR numbers anywhere in the change
description.

Author: Gudahtt

src/update-changelog.ts

@@ -88,7 +88,7 @@ function getAllLoggedPrNumbers(changelog: Changelog) {
   const prNumbersWithChangelogEntries = [];
   for (const description of changeDescriptions) {
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-    const matchResults = description!.match(/^\[#(\d+)\]/u);
+    const matchResults = description!.match(/\[#(\d+)\]/u);
     if (matchResults === null) {
       continue;
     }