bump-revision: handle array of licenses

Allowing multiple licenses meant that `formula.license` returned an
array. This converts that array to the appropriate format for
`bump-revision`

Library/Homebrew/dev-cmd/bump-revision.rb

@@ -42,9 +42,14 @@ module Homebrew
       end
 
       old = if formula.license
+        license_string = if formula.license.length > 1
+          formula.license
+        else
+          "\"#{formula.license.first}\""
+        end
         # insert replacement revision after license
         <<~EOS
-          license "#{formula.license}"
+          license #{license_string}
         EOS
       elsif formula.path.read.include?("stable do\n")
         # insert replacement revision after homepage