ruby: remove warnings on unused parameters

These warnings may be enabled again in future when Ruby itself will be fixed.

src/plugins/ruby/CMakeLists.txt

@@ -24,6 +24,10 @@ add_library(ruby MODULE
 set_target_properties(ruby PROPERTIES PREFIX "")
 
 if(RUBY_FOUND)
+  # temporary fix: ignore all warnings on unused parameters due to warnings
+  # caused by Ruby headers (with Ruby ≥ 3.1.0)
+  # see: https://github.com/ruby/ruby/pull/7085
+  add_definitions(-Wno-unused-parameter)
   include_directories(${RUBY_INCLUDE_DIRS})
   target_link_libraries(ruby ${RUBY_LDFLAGS} weechat_plugins_scripts coverage_config)
 endif(RUBY_FOUND)