Put back a needed env var

Author: rgommers

.github/workflows/wheels.yml

@@ -80,6 +80,9 @@ jobs:
           - buildplat: [ macos13, macosx_x86_64, openblas ]
             python: "cp314t"
 
+    env:
+      IS_32_BIT: ${{ matrix.buildplat[1] == 'win32' }}  # used in a cibw_*.sh script
+
     steps:
       - name: Checkout numpy-release
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2