Updated .rubocop.yml to fix Style/TrailingComma deprecation error

and fixed rubocop errors

.rubocop.yml

@@ -23,5 +23,8 @@ Style/SpecialGlobalVars:
 Style/StringLiterals:
   EnforcedStyle: double_quotes
 
-Style/TrailingComma:
+Style/TrailingCommaInLiteral:
+  Enabled: false
+
+Style/TrailingCommaInArguments:
   Enabled: false

lib/bashcov/lexer.rb

@@ -3,13 +3,13 @@ module Bashcov
   # coverage
   class Lexer
     # Lines starting with one of these tokens are irrelevant for coverage
-    IGNORE_START_WITH = %w(# function)
+    IGNORE_START_WITH = %w(# function).freeze
 
     # Lines ending with one of these tokens are irrelevant for coverage
-    IGNORE_END_WITH = %w|(|
+    IGNORE_END_WITH = %w|(|.freeze
 
     # Lines containing only one of these keywords are irrelevant for coverage
-    IGNORE_IS = %w(esac if then else elif fi while do done { } ;;)
+    IGNORE_IS = %w(esac if then else elif fi while do done { } ;;).freeze
 
     # @param [String] filename File to analyze
     # @param [Hash] coverage Coverage with executed lines marked

lib/bashcov/runner.rb

@@ -15,7 +15,10 @@ def run
       @xtrace = Xtrace.new
       fd = @xtrace.file_descriptor
       options = { :in => :in, fd => fd } # bind FDs to the child process
-      options.merge!(out: "/dev/null", err: "/dev/null") if Bashcov.options.mute
+      if Bashcov.options.mute
+        options[:out] = "/dev/null"
+        options[:err] = "/dev/null"
+      end
       env = { "BASH_XTRACEFD" => fd.to_s, "PS4" => Xtrace::PS4 }
 
       command_pid = Process.spawn env, @command, options # spawn the command

lib/bashcov/xtrace.rb

@@ -8,10 +8,10 @@ module Bashcov
   class Xtrace
     # [String] Character that will be used to indicate the nesting level of
     #   +xtrace+d instructions
-    DEPTH_CHAR = "+"
+    DEPTH_CHAR = "+".freeze
 
     # [String] Prefix used in +PS4+ to identify relevant output
-    PREFIX = "BASHCOV>"
+    PREFIX = "BASHCOV>".freeze
 
     # [String] A randomly-generated token for delimiting the fields of the
     #   +{PS4}+