`improved-yarn-audit` has been updated so that it supports GitHub
advisories. Two new GitHub advisories have been ignored, as they are
both moderate RegExp DoS vulnerabilities that don't affect us, and they
are embedded deep within our dependency graph and are difficult to
update.
The `.sh` file extension is now used for all Bash scripts. This ensures
the files are recognized as Bash scripts by the ShellCheck CI job, and
by editors/IDEs for improved syntax highlighting.
