Update GitHub Actions runner to macOS 14 (#3450)

Removing dependency on self-hosted macOS runners, in prep for migration
to meta-pytorch org

Author: ZainRizvi

.github/workflows/mps-tests.yml

@@ -36,7 +36,7 @@ jobs:
         pytorch-channel: ["pytorch"]
         skip-distrib-tests: [1]
       fail-fast: false
-    runs-on: ["macos-m1-stable"]
+    runs-on: ["macos-14"]
     timeout-minutes: 60
 
     steps:
@@ -71,7 +71,7 @@ jobs:
       - name: Install uv
         shell: bash -l {0}
         run: |
-          conda shell.bash hook
+          eval "$(conda shell.bash hook)"
           conda activate $CONDA_ENV
           pip install uv
 
@@ -85,23 +85,23 @@ jobs:
         if: ${{ matrix.pytorch-channel == 'pytorch' }}
         shell: bash -l {0}
         run: |
-          conda shell.bash hook
+          eval "$(conda shell.bash hook)"
           conda activate $CONDA_ENV
           uv pip install torch torchvision
 
       - name: Install PyTorch (nightly)
         if: ${{ matrix.pytorch-channel == 'pytorch-nightly' }}
         shell: bash -l {0}
         run: |
-          conda shell.bash hook
+          eval "$(conda shell.bash hook)"
           conda activate $CONDA_ENV
           uv pip install --pre torch torchvision --index-url https://download.pytorch.org/whl/nightly/cpu
 
       - name: Install dependencies
         shell: bash -l {0}
         working-directory: ${{ github.repository }}
         run: |
-          conda shell.bash hook
+          eval "$(conda shell.bash hook)"
           conda activate $CONDA_ENV
           # TODO: We add set -xe to explicitly fail the CI if one of the commands is failing.
           # Somehow the step is passing even if a subcommand failed
@@ -129,7 +129,7 @@ jobs:
         shell: bash -l {0}
         working-directory: ${{ github.repository }}
         run: |
-          conda shell.bash hook
+          eval "$(conda shell.bash hook)"
           conda activate $CONDA_ENV
           SKIP_DISTRIB_TESTS=${{ matrix.skip-distrib-tests }} bash tests/run_cpu_tests.sh
 
@@ -144,6 +144,6 @@ jobs:
         shell: bash -l {0}
         working-directory: ${{ github.repository }}
         run: |
-          conda shell.bash hook
+          eval "$(conda shell.bash hook)"
           conda activate $CONDA_ENV
           python examples/mnist/mnist.py --epochs=1