ci: Move NumPy version into a variable.

Author: QuLogic

.github/workflows/cibuildwheel.yml

@@ -12,14 +12,16 @@ jobs:
   build_wheels:
     name: Build wheels on ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
+    env:
+      min-numpy-version: "1.16.0"
+      min-numpy-hash: "04/b6/d7faa70a3e3eac39f943cc6a6a64ce378259677de516bd899dd9eb8f9b32"
     strategy:
       matrix:
         os: [ubuntu-18.04, windows-latest, macos-latest]
         cibw_archs: ["auto"]
         include:
           - os: ubuntu-18.04
             cibw_archs: "aarch64"
-            numpy-version: "1.16"
 
     steps:
       - name: Set up QEMU
@@ -41,18 +43,18 @@ jobs:
         id: numpy-aarch64-cache
         with:
           path: numpy-aarch64-cache/
-          key: numpy-aarch64-cache-${{ matrix.numpy-version }}
+          key: numpy-aarch64-cache-${{ env.min-numpy-version }}
 
       - name: Install cibuildwheel
         run: |
           python -m pip install cibuildwheel==1.9.0
 
-      - name: Build numpy 1.16 for aarch64
+      - name: Build minimum NumPy for aarch64
         if: matrix.cibw_archs == 'aarch64' && steps.numpy-aarch64-cache.outputs.cache-hit != 'true'
         run: |
-          wget https://files.pythonhosted.org/packages/04/b6/d7faa70a3e3eac39f943cc6a6a64ce378259677de516bd899dd9eb8f9b32/numpy-1.16.0.zip
-          unzip numpy-1.16.0.zip
-          cd numpy-1.16.0
+          wget https://files.pythonhosted.org/packages/${{ env.min-numpy-hash }}/numpy-${{ env.min-numpy-version }}.zip
+          unzip numpy-${{ env.min-numpy-version }}.zip
+          cd numpy-${{ env.min-numpy-version }}
           python -m cibuildwheel --output-dir ../numpy-aarch64-cache
         env:
           CIBW_BUILD: "cp36-* cp37-* cp38-*"
@@ -80,7 +82,7 @@ jobs:
           CIBW_BUILD: "cp37-* cp38-*"
           CIBW_MANYLINUX_X86_64_IMAGE: manylinux1
           CIBW_MANYLINUX_I686_IMAGE: manylinux1
-          CIBW_BEFORE_BUILD: pip install certifi; pip install --find-links=numpy-aarch64-cache/ numpy==1.16
+          CIBW_BEFORE_BUILD: pip install certifi; pip install --find-links=numpy-aarch64-cache/ numpy==${{ env.min-numpy-version }}
           MPL_DISABLE_FH4: "yes"
           CIBW_ARCHS: ${{ matrix.cibw_archs }}
 
@@ -91,7 +93,7 @@ jobs:
           CIBW_BUILD: "cp36-*"
           CIBW_MANYLINUX_X86_64_IMAGE: manylinux1
           CIBW_MANYLINUX_I686_IMAGE: manylinux1
-          CIBW_BEFORE_BUILD: pip install certifi; pip install --find-links=numpy-aarch64-cache/ numpy==1.16
+          CIBW_BEFORE_BUILD: pip install certifi; pip install --find-links=numpy-aarch64-cache/ numpy==${{ env.min-numpy-version }}
           MPL_DISABLE_FH4: "yes"
           CIBW_ARCHS: ${{ matrix.cibw_archs }}
         if: >
@@ -103,7 +105,7 @@ jobs:
           python -m cibuildwheel --output-dir dist
         env:
           CIBW_BUILD: "pp3?-*"
-          CIBW_BEFORE_BUILD: pip install certifi numpy==1.16
+          CIBW_BEFORE_BUILD: pip install certifi numpy==${{ env.min-numpy-version }}
           CIBW_ARCHS: ${{ matrix.cibw_archs }}
         if: >
           runner.os != 'Windows' && (