Drop remaining uses of Intel macOS in CI (#4430)

We've been working through the CI setups for the other K components and
removing support for Intel macOS; this PR finishes the process by
removing support from K itself.

There are a couple of places where we can simplify conditional checks in
workflow steps, and one place where it makes sense to run a job on
`macos-14` (which will be arm64).

.github/workflows/release.yml

@@ -50,8 +50,6 @@ jobs:
         include:
           - runner: ubuntu-24.04
             os: ubuntu-24.04
-          - runner: macos-13
-            os: macos-13
           - runner: MacM1
             os: self-macos-12
     runs-on: ${{ matrix.runner }}

.github/workflows/test-pr.yml

@@ -125,7 +125,7 @@ jobs:
     name: 'Pyk: Nix Build'
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-13]
+        os: [ubuntu-latest, macos-14]
     defaults:
       run:
         working-directory: ./pyk
@@ -134,7 +134,6 @@ jobs:
       - name: 'Check out code'
         uses: actions/checkout@v4
       - name: 'Install Nix'
-        if: ${{ !startsWith(matrix.os, 'self') }}
         uses: cachix/install-nix-action@v22
         with:
           install_url: https://releases.nixos.org/nix/nix-2.13.3/install
@@ -143,7 +142,6 @@ jobs:
             substituters = http://cache.nixos.org https://hydra.iohk.io
             trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=
       - name: 'Install Cachix'
-        if: ${{ !startsWith(matrix.os, 'self') }}
         uses: cachix/cachix-action@v14
         with:
           name: k-framework
@@ -161,8 +159,6 @@ jobs:
       matrix:
         include:
           - runner: [self-hosted, linux, normal]
-          - runner: macos-13
-            os: macos-13
           - runner: MacM1
             os: self-macos-12
     runs-on: ${{ matrix.runner }}