Run pip under correct arch in macOS CI

Author: topolarity

.github/workflows/system.yml

@@ -53,7 +53,12 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
           architecture: ${{ matrix.architecture }}
-      - run: python -m pip install --user numpy
+      - name: Install numpy
+        run: python -m pip install --user numpy
+        if: ${{ !(matrix.os == 'macos-latest' && matrix.architecture == 'x64') }}
+      - name: Install numpy (macOS x64 — run pip under Rosetta for x86_64 wheels)
+        run: arch -x86_64 python -m pip install --user numpy
+        if: ${{ matrix.os == 'macos-latest' && matrix.architecture == 'x64' }}
       - run: python -m pip install virtualenv
       - run: virtualenv --version
       - name: Setup julia