Update Xcode version from 13.0 to 13.1 (#901)

Author: ferologics

.github/workflows/ci.yml

@@ -16,15 +16,15 @@ jobs:
         xcode:
           - '12.4'
           - '12.5.1'
-          - '13.0'
+          - '13.1'
     steps:
       - uses: actions/checkout@v2
       - name: Select Xcode ${{ matrix.xcode }}
         run: sudo xcode-select -s /Applications/Xcode_${{ matrix.xcode }}.app
       - name: Run tests
         run: make test-library
       - name: Compile documentation
-        if: ${{ matrix.xcode == '13.0' }}
+        if: ${{ matrix.xcode == '13.1' }}
         run: make test-docs
       - name: Run benchmark
         run: make benchmark
@@ -36,7 +36,7 @@ jobs:
         xcode:
           - '12.4'
           - '12.5.1'
-          - '13.0'
+          - '13.1'
     steps:
       - uses: actions/checkout@v2
       - name: Select Xcode ${{ matrix.xcode }}