PR checks: stop setting experimental Swift var for new CLI versions (g…

…ithub#1718)

Now that `latest` and `cached` are both 2.13.3, which is the version in which we GA'ed Swift, we should stop setting this experimental variable when we test these CLI versions so we can test the case where the variable is unset.

Merge pull request github#1687 from github/henrymercer/update-changel…

…og-note

Push back semver CodeQL bundles

Merge pull request github#1675 from shaikhul/remove-consts

Remove MismatchedBranches check from code scanning workflow validation