Update package name

With Block Class and External Links installed on a D9 site, there are two instances of "User interface" on the Extend page.

Block Class uses: User Interface (capital "I")
External links uses: User Interface (lowercase "i")

Based on drupal.org/node/542202#package and groups.drupal.org/node/97054, it appears as though the "standard" is for the first letter in the second word to be lowercase. Small patch to come to make this minor change so that only one instance of "User interface" is displayed on the Extend page.