Remove unnecessary freeze calls on literal strings

Now that we no longer support Ruby 2.2, we can remove these redundant
`freeze` calls since we specify `frozen_string_literal` at the top of
these files.

Author: sds

lib/overcommit/constants.rb

@@ -3,10 +3,10 @@
 # Global application constants.
 module Overcommit
   HOME = File.expand_path(File.join(File.dirname(__FILE__), '..', '..')).freeze
-  CONFIG_FILE_NAME = '.overcommit.yml'.freeze
+  CONFIG_FILE_NAME = '.overcommit.yml'
 
   HOOK_DIRECTORY = File.join(HOME, 'lib', 'overcommit', 'hook').freeze
 
-  REPO_URL = 'https://github.com/brigade/overcommit'.freeze
-  BUG_REPORT_URL = "#{REPO_URL}/issues".freeze
+  REPO_URL = 'https://github.com/brigade/overcommit'
+  BUG_REPORT_URL = "#{REPO_URL}/issues"
 end

lib/overcommit/hook/pre_commit/berksfile_check.rb

@@ -6,7 +6,7 @@ module Overcommit::Hook::PreCommit
   #
   # @see http://berkshelf.com/
   class BerksfileCheck < Base
-    LOCK_FILE = 'Berksfile.lock'.freeze
+    LOCK_FILE = 'Berksfile.lock'
 
     def run
       # Ignore if Berksfile.lock is not tracked by git

lib/overcommit/hook/pre_commit/bundle_audit.rb

@@ -5,7 +5,7 @@ module Overcommit::Hook::PreCommit
   #
   # @see https://github.com/rubysec/bundler-audit
   class BundleAudit < Base
-    LOCK_FILE = 'Gemfile.lock'.freeze
+    LOCK_FILE = 'Gemfile.lock'
 
     def run
       # Ignore if Gemfile.lock is not tracked by git

lib/overcommit/hook/pre_commit/bundle_check.rb

@@ -6,7 +6,7 @@ module Overcommit::Hook::PreCommit
   #
   # @see http://bundler.io/
   class BundleCheck < Base
-    LOCK_FILE = 'Gemfile.lock'.freeze
+    LOCK_FILE = 'Gemfile.lock'
 
     def run
       # Ignore if Gemfile.lock is not tracked by git

lib/overcommit/hook/pre_commit/bundle_outdated.rb

@@ -6,7 +6,7 @@ module Overcommit::Hook::PreCommit
   #
   # @see http://bundler.io/bundle_outdated.html
   class BundleOutdated < Base
-    LOCK_FILE = 'Gemfile.lock'.freeze
+    LOCK_FILE = 'Gemfile.lock'
 
     def run
       # Ignore if Gemfile.lock is not tracked by git

lib/overcommit/hook/pre_commit/yarn_check.rb

@@ -6,7 +6,7 @@ module Overcommit::Hook::PreCommit
   #
   # @see https://yarnpkg.com/en/docs/cli/check
   class YarnCheck < Base
-    LOCK_FILE = 'yarn.lock'.freeze
+    LOCK_FILE = 'yarn.lock'
 
     # A lot of the errors returned by `yarn check` are outside the developer's control
     # (are caused by bad package specification, in the hands of the upstream maintainer)

lib/overcommit/hook_context/prepare_commit_msg.rb

@@ -16,7 +16,7 @@ def commit_message_filename
     # exists); or commit, followed by a commit SHA-1 (if a -c, -C or --amend
     # option was given)
     def commit_message_source
-      @args[1].to_sym if @args[1]
+      @args[1]&.to_sym
     end
 
     # Returns the commit's SHA-1.

lib/overcommit/message_processor.rb

@@ -8,12 +8,12 @@ module Overcommit
   # output tuple from an array of {Overcommit::Hook::Message}s, respecting the
   # configuration settings for the given hook.
   class MessageProcessor
-    ERRORS_MODIFIED_HEADER = 'Errors on modified lines:'.freeze
-    WARNINGS_MODIFIED_HEADER = 'Warnings on modified lines:'.freeze
-    ERRORS_UNMODIFIED_HEADER = "Errors on lines you didn't modify:".freeze
-    WARNINGS_UNMODIFIED_HEADER = "Warnings on lines you didn't modify:".freeze
-    ERRORS_GENERIC_HEADER = 'Errors:'.freeze
-    WARNINGS_GENERIC_HEADER = 'Warnings:'.freeze
+    ERRORS_MODIFIED_HEADER = 'Errors on modified lines:'
+    WARNINGS_MODIFIED_HEADER = 'Warnings on modified lines:'
+    ERRORS_UNMODIFIED_HEADER = "Errors on lines you didn't modify:"
+    WARNINGS_UNMODIFIED_HEADER = "Warnings on lines you didn't modify:"
+    ERRORS_GENERIC_HEADER = 'Errors:'
+    WARNINGS_GENERIC_HEADER = 'Warnings:'
 
     # @param hook [Overcommit::Hook::Base]
     # @param unmodified_lines_setting [String] how to treat messages on

lib/overcommit/utils.rb

@@ -297,7 +297,7 @@ def matches_path?(pattern, path)
       #
       # @param args [Array<String>]
       def debug(*args)
-        log.debug(*args) if log
+        log&.debug(*args)
       end
     end
   end

lib/overcommit/version.rb

@@ -2,5 +2,5 @@
 
 # Defines the gem version.
 module Overcommit
-  VERSION = '0.47.0'.freeze
+  VERSION = '0.47.0'
 end