Require system gems in api-deps package

Rake and Rack need to get installed on the system and not
with the bundled_gems archive because we require them for passenger.
This caused that an update of one of these gems in the Gemfile did not trigger
an update of the system gem when updating the RPM package which causes
a crash of the whole application.

Therefore we require them now. There are only 2 gems so it is reasonable to update
the version in the spec file manually for now when we update the gem. The RPM package
build will fail if we don't do it and prevents us from deploying and breaking our instance.

dist/obs-bundled-gems.spec

@@ -51,6 +51,7 @@ This package bundles all the gems required by the Open Build Service
 to make it easier to deploy the obs-server package.
 
 %define rake_version 12.3.1
+%define rack_version 2.0.6
 
 %package -n obs-api-deps
 Summary:        Holding dependencies required to run the OBS frontend
@@ -63,6 +64,7 @@ Requires:       sphinx >= 2.1.8
 Requires:       perl(GD)
 Requires:       rubygem(ruby:2.5.0:bundler)
 Requires:       rubygem(ruby:2.5.0:rake:%{rake_version})
+Requires:       rubygem(ruby:2.5.0:rack:%{rack_version})
 
 %description -n obs-api-deps
 To simplify splitting the test suite packages off the main package,
@@ -102,8 +104,9 @@ bundle config build.nokogiri --use-system-libraries
 %install
 bundle --local --path %{buildroot}%_libdir/obs-api/
 
-# test that the rake_version macro is still matching our Gemfile
+# test that the rake and rack macros is still matching our Gemfile
 test -f %{buildroot}%_libdir/obs-api/ruby/2.5.0/gems/rake-%{rake_version}/rake.gemspec
+test -f %{buildroot}%_libdir/obs-api/ruby/2.5.0/gems/rack-%{rack_version}/rack.gemspec
 
 # run gem clean up script
 /usr/lib/rpm/gem_build_cleanup.sh %{buildroot}%_libdir/obs-api/ruby/*/