(CAT-2281) Remove puppet 7 infrastructure

Puppet 7 is EOL. Therefore, we can remove the test infrastructure for it.
This commit aims to clear up any testing/config infrastructure related to
Puppet 7 and, by extension, Ruby 2.7.

Author: LukasAud

.github/workflows/ci.yml

@@ -18,11 +18,8 @@ jobs:
       fail-fast: false
       matrix:
         ruby_version:
-          - '2.7'
           - '3.2'
         include:
-          - ruby_version: '2.7'
-            puppet_version: '~> 7.0'
           - ruby_version: '3.2'
             puppet_version: '~> 8.0'
         runs-on: 

.github/workflows/nightly.yml

@@ -11,11 +11,8 @@ jobs:
       fail-fast: false
       matrix:
         ruby_version:
-          - '2.7'
           - '3.2'
         include:
-          - ruby_version: '2.7'
-            puppet_version: '~> 7.0'
           - ruby_version: '3.2'
             puppet_version: '~> 8.0'
         runs-on: