Different tests for linux vs. not linux

Only use xvfb on Linu

.github/workflows/test-with-pip.yml

@@ -52,16 +52,32 @@ jobs:
         run: pip install celiagg
       - name: Sanity check package version
         run: pip list
-      - name: Run kiva test suite
+      - name: Run kiva test suite (Linux)
         env:
           PYTHONFAULTHANDLER: 1
           ETS_QT4_IMPORTS: 1
         run: xvfb-run python -m unittest discover -v kiva
+        if: matrix.os == 'ubuntu-latest'
         working-directory: ${{ runner.temp }}
-      - name: Run enable test suite
+      - name: Run kiva test suite (not Linux)
+        env:
+          PYTHONFAULTHANDLER: 1
+          ETS_QT4_IMPORTS: 1
+        run: python -m unittest discover -v kiva
+        if: matrix.os != 'ubuntu-latest'
+        working-directory: ${{ runner.temp }}
+      - name: Run enable test suite (Linux)
         env:
           PYTHONFAULTHANDLER: 1
           ETS_QT4_IMPORTS: 1
         # kiva agg requires at least 15-bit color depth.
         run: xvfb-run --server-args="-screen 0 1024x768x24" python -m unittest discover -v enable
+        if: matrix.os == 'ubuntu-latest'
+        working-directory: ${{ runner.temp }}
+      - name: Run enable test suite (not Linux)
+        env:
+          PYTHONFAULTHANDLER: 1
+          ETS_QT4_IMPORTS: 1
+        run: python -m unittest discover -v enable
+        if: matrix.os != 'ubuntu-latest'
         working-directory: ${{ runner.temp }}