Fix gem_pins_spec.rb to use the renamed DocMap#cache_doc_map_gems!

Earlier, while this PR's PinCache-core piece was still a standalone
branch (before combining the engine, wiring, and CLI update into one
PR), this spec was pointed at DocMap#cache_all! since that was the
only name that existed on master at the time. Now that this PR also
includes the DocMap wiring that renames cache_all! to
cache_doc_map_gems!, the spec needs to follow that rename too - CI
caught the drift (undefined method 'cache_all!' for an instance of
Solargraph::DocMap).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: apiology

spec/gem_pins_spec.rb

@@ -6,7 +6,7 @@
   let(:pin) { doc_map.pins.find { |pin| pin.path == path } }
 
   before do
-    doc_map.cache_all!(STDERR) # rubocop:disable Style/GlobalStdStream
+    doc_map.cache_doc_map_gems!(STDERR) # rubocop:disable Style/GlobalStdStream
   end
 
   context 'with a combined method pin' do