Small changes:

- Add statistics output example
 - Fix various compilation warnings
 - Test/bump ruby version to 3.2
 - Fix failing test under OSX

FossilOrigin-Name: c5c6d745d854082b8704c8da61dcc315dbc3d99b8ceec4a82ebea65e861f10ea

spec/mdbx/database_spec.rb

@@ -71,7 +71,10 @@ RSpec.describe( MDBX::Database ) do
 			# here for behavior.
 			expect {
 				described_class.open( TEST_DATABASE.to_s )
-            }.to raise_exception( MDBX::DatabaseError, /resource \w+ unavailable/i )
+            }.to raise_exception(
+              MDBX::DatabaseError,
+              /(?:resource \w+ unavailable|environment is already used)/i
+            )
 		end
 	end