[Ruby] backport: update bundle before building the native lib (#38334)

Backport #38303 to the 1.69.x branch.

Co-authored-by: alto-ruby <[email protected]>

Author: markdroth

Rakefile

@@ -184,7 +184,7 @@ task 'gem:native', [:plat] do |t, args|
     run_rake_compiler(plat, <<~EOT)
       #{prepare_ccache_cmd} && \
       gem update --system --no-document && \
-      bundle && \
+      bundle update && \
       bundle exec rake clean && \
       bundle exec rake native:#{plat} pkg/#{spec.full_name}-#{plat}.gem pkg/#{spec.full_name}.gem \
         RUBY_CC_VERSION=#{ruby_cc_versions} \
@@ -216,7 +216,7 @@ task 'gem:native', [:plat] do |t, args|
     run_rake_compiler(plat, <<~EOT)
       #{prepare_ccache_cmd} && \
       gem update --system --no-document && \
-      bundle && \
+      bundle update && \
       bundle exec rake clean && \
       export GRPC_RUBY_DEBUG_SYMBOLS_OUTPUT_DIR=#{debug_symbols_dir} && \
       bundle exec rake native:#{plat} pkg/#{spec.full_name}-#{plat}.gem pkg/#{spec.full_name}.gem \