Add clang v20 and change default version to v16

.github/workflows/self-test.yml

@@ -31,7 +31,7 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-latest, macos-latest, windows-latest ]
-        clang-version: ['9','10', '11', '12', '13', '14', '15', '16', '17', '18', '19']
+        clang-version: ['8','9','10', '11', '12', '13', '14', '15', '16', '17', '18', '19', '20']
       fail-fast: false
     runs-on: ${{ matrix.os }}
     steps:

action.yml

@@ -39,12 +39,12 @@ inputs:
   version:
     description: |
       The desired version of the [clang-tools](https://github.com/cpp-linter/clang-tools-pip) to use.
-      Accepted options are strings which can be 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8 or 7.
+      Accepted options are strings which can be 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, or 8.
 
       - Set this option to a blank string (`''`) to use the platform's default installed version.
       - This value can also be a path to where the clang tools are installed (if using a custom install location).
     required: false
-    default: 14
+    default: 16
   verbosity:
     description: |
       This controls the action's verbosity in the workflow's logs.