mailcatcher: fix missing assets

[sj26]

Without this step the user interface does not function because the javascript and stylesheets are not compiled or included, so cannot be served to browsers.

This command was run in the formula for v0.9.0 but was removed in the update to v0.10.0 (#173471):

104b175#diff-aff4c5be3f339d85e769e3c2362bb626acfde080d57d0bb75f42551ecc3d0413L161

Closes sj26/mailcatcher#560.

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• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

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[sj26]

This isn't going to work as-is because the compile-dependencies aren't installed.

It looks like swiftgen installs bundler for use at build time:

homebrew-core/Formula/s/swiftgen.rb

Lines 24 to 38 in 9643970

	# Install bundler (needed for our rake tasks)
	ENV["GEM_HOME"] = buildpath/"gem_home"
	# we use the macOS ruby (2.6.10p210 (2022-04-12 revision 67958)) this is the last supported bundler version
	system "gem", "install", "bundler", "-v 2.4.22"
	ENV.prepend_path "PATH", buildpath/"gem_home/bin"
	system "bundle", "install", "--without", "development", "release"
	# Disable linting
	ENV["NO_CODE_LINT"] = "1"
	# Install SwiftGen in `libexec` (because of our resource bundle)
	# Then create a script to invoke it
	system "bundle", "exec", "rake", "cli:install[#{libexec}]"

Maybe this should do the same.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[idapartners]

This seems to have been closed due to lack of activity, but ... it's still an issue. How do we re-open it?