Fix case-insensitive finding of LICENSE.*.TXT (bsc#1215698)

Ruby 3.1 drops the formerly working FNM_CASEFOLD for `Dir.glob`
but it keeps working for `File.fnmatch?`

library/packages/src/lib/y2packager/licenses_fetchers/archive.rb

@@ -42,7 +42,7 @@ def locales
           begin
             unpack_archive
 
-            license_files = Dir.glob(File.join(archive_dir, "**", "LICENSE.*.TXT"), File::FNM_CASEFOLD)
+            license_files = find_case_insensitive(archive_dir, "LICENSE.*.TXT")
             # NOTE: despite the use of the case-insensitive flag, the captured group will be
             # returned as it is.
             languages = license_files.map { |path| path[/LICENSE.(\w*).TXT/i, 1] }
@@ -160,7 +160,15 @@ def fallback_path(directory)
       #
       # @return [String, nil] The file path; nil if was not found
       def find_path_for(directory, file)
-        Dir.glob(File.join(directory, "**", file), File::FNM_CASEFOLD).first
+        find_case_insensitive(directory, file).first
+      end
+
+      # TODO: doc, test
+      def find_case_insensitive(directory, fileglob)
+        files = Dir.glob(File.join(directory, "**", "*"))
+        files.find_all do |fn|
+          File.fnmatch?(File.join(directory, "**", fileglob), fn, File::FNM_CASEFOLD)
+        end
       end
     end
   end