fixup! ci(osx): use new location of the perforce cask

It still fails! *Still!*

Even after upgrading the cask's definition in the PR
Homebrew/homebrew-cask#70981 does it fail.

The explanation is, as Gábor Szeder dug out from the commit history:
the local definitions might get stale and need to be updated.

So let's just update them in case `brew cask install perforce` fails,
and just try again!

This will still fail, of course, when `homebrew-cask` falls behind
Perforce's release schedule. But once it is updated, we can now simply
re-run the failed jobs and they will pick up that update.

As to updating `homebrew-cask`: I started automating this, via
https://dev.azure.com/gitgitgadget/git/_build?definitionId=11&_a=summary
(I plan on finishing it once the next Perforce upgrade comes around.)

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

ci/install-dependencies.sh

@@ -40,7 +40,11 @@ osx-clang|osx-gcc)
 	test -z "$BREW_INSTALL_PACKAGES" ||
 	brew install $BREW_INSTALL_PACKAGES
 	brew link --force gettext
-	brew cask install perforce ||
+	brew cask install perforce || {
+		# Update the definitions and try again
+		git -C "$(brew --repository)"/Library/Taps/homebrew/homebrew-cask pull &&
+		brew cask install perforce
+	} ||
 	brew install caskroom/cask/perforce
 	case "$jobname" in
 	osx-gcc)