Add PR check using pip install method.

This is necessary because it seems that font differences between the conda
installed version and the pip installed version can change test results.  The
release is done all with pip, and it's vital that the PR process has a step
that is the same as the release process.

.github/workflows/python-package-pr-pip.yaml

@@ -0,0 +1,33 @@
+name: Build and Test using pip (PR)
+
+on:
+  pull_request:
+    branches: [ '**' ]
+
+jobs:
+  build_and_test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          # Need to clone everything to determine version from git.
+          fetch-depth: 0
+
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: "3.10"
+          cache: "pip"
+          cache-dependency-path: "setup.cfg"
+
+      - name: Build and install
+        run: |
+          python -m pip install --upgrade pip setuptools
+          python -m pip install pytest
+          if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+          python -m pip install .
+      - name: Run tests
+        run: |
+          cd tests
+          pytest