Remove macOS-11 from the matrix (#144)

* Remove macOS-11 from the matrix
Closes #143 
Infra decommissioned in GH Actions

Author: andrewdavidmackenzie

.github/workflows/clippy_build_test.yml

@@ -24,16 +24,13 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ ubuntu-latest, macos-11, macos-12, macos-13, macos-14 ]
+        os: [ ubuntu-latest, macos-12, macos-13, macos-14 ]
         rust: [stable, beta, 1.72.0] # Minimum Rust Version Supported = 1.72.0
         experimental: [false]
         include:
           - os: ubuntu-latest
             rust: nightly
             experimental: true
-          - os: macos-11
-            rust: nightly
-            experimental: true
           - os: macos-12
             rust: nightly
             experimental: true