ci: Use pypa/gh-action-pypi-publish and trusted publishing

Steps needed to make this work:
1. GitHub: Create environment (only the name is necessary):
   https://github.com/JonathonReinhart/staticx/settings/environments/
2. PyPI: Add Trusted Publisher:
   https://test.pypi.org/manage/project/staticx/settings/publishing/

.github/workflows/publish-main.yml

@@ -6,10 +6,11 @@ on:
     #branches:
     #  - main
 
+# TODO: De-duplicate with build-test.yml
 # TODO: De-duplicate with python-publish-release.yml
 
 jobs:
-  deploy:
+  build:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout code
@@ -27,7 +28,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install setuptools wheel twine
+        pip install setuptools wheel
 
         sudo apt-get update
         sudo apt-get install -y musl-tools scons
@@ -38,8 +39,33 @@ jobs:
         CI_VERSION_BUILD_NUMBER: ${{ github.run_id }}
       run: python setup.py sdist bdist_wheel
 
+    - name: Upload artifacts
+      uses: actions/upload-artifact@v3
+      with:
+        name: python-dist
+        path: dist/
+
+
+  pypi-publish:
+    name: Upload release to Test PyPI
+    runs-on: ubuntu-latest
+    environment:
+      name: TestPyPI
+      url: https://test.pypi.org/project/staticx/
+    permissions:
+      id-token: write  # IMPORTANT: this permission is mandatory for trusted publishing
+    steps:
+    - name: Download artifacts
+      uses: actions/download-artifact@v3
+      with:
+        name: python-dist
+        path: dist/
+
+    - name: Display downloaded files
+      run: ls -R
+
     - name: Publish
-      env:
-        TWINE_USERNAME: ${{ secrets.PYPI_TEST_USERNAME }}
-        TWINE_PASSWORD: ${{ secrets.PYPI_TEST_PASSWORD }}
-      run: twine upload --repository-url https://test.pypi.org/legacy/ dist/*
+      uses: pypa/gh-action-pypi-publish@release/v1
+      with:
+        print-hash: true
+        repository-url: https://test.pypi.org/legacy/