chore: fix a typo (#104)

Author: rubyconvict

with_advisory_lock.gemspec

@@ -16,7 +16,7 @@ Gem::Specification.new do |spec|
   spec.files         = `git ls-files`.split($INPUT_RECORD_SEPARATOR)
   spec.test_files    = spec.files.grep(%r{^test/})
   spec.require_paths = %w[lib]
-  spec.metadata      = { 'rubyspecs_mfa_required' => 'true' }
+  spec.metadata      = { 'rubygems_mfa_required' => 'true' }
   spec.required_ruby_version = '>= 2.7.0'
   spec.metadata['yard.run'] = 'yri'