Limit NPY_PROMOTION_STATE to i386 test job only (#552)

As discussed in #548, we need to fix a failing test.

This PR removes the global `NPY_PROMOTION_STATE: weak_and_warn`
environment variable and applies it only to the `test-deb11-i386` job
where overflow errors are most likely to occur in the 32-bit
environment.

Addresses test overflow errors seen in #544. Note that the
`test-deb11-i386` job is not failing.

Author: Benjamin Moody

.github/workflows/test.yml

@@ -8,9 +8,6 @@ on:
     branches:
       - main
 
-env:
-  NPY_PROMOTION_STATE: weak_and_warn
-
 jobs:
   test:
     name: Python ${{ matrix.python-version }} / ${{ matrix.os }} / ${{ matrix.numpy }}
@@ -40,6 +37,8 @@ jobs:
     name: Python 3.7 on Debian 11 i386
     runs-on: ubuntu-latest
     container: i386/debian:11
+    env:
+      NPY_PROMOTION_STATE: weak_and_warn
     steps:
       - name: Install dependencies
         run: |