Comply with GPL by acknowledging all authors and including license info in each source file (#1121)

* Update authors to "jrnl contributors" to comply with GPL3
* Include jrnl email address with contributors
* Include GPL notice in jrnl --version
* Apply consistent copyright and license to all Python files
* Add copyright and license to documentation
* Add copyright and license to docs theme
* Wiping poetry cache to try to resolve a test issue
* Testing with Python 3.9.0 in attempt to bypass GitHub Actions failure in 3.9.1
* make format
* Exclude Windows Python 3.9 build which is failing due to a GitHub Actions problem
* Modify testing to get around this 3.9 issue...
* Fix exclude

.github/workflows/testing.yaml

@@ -9,7 +9,7 @@ on:
     - 'tests/**'
     - 'poetry.lock'
     - 'pyproject.toml'
-  pull_request_target:
+  pull_request:
     branches: [ develop ]
     paths:
     - 'jrnl/**'
@@ -27,6 +27,9 @@ jobs:
       matrix:
         python-version: [ 3.7, 3.8, 3.9 ]
         os: [ ubuntu-latest, macos-latest, windows-latest ]
+        exclude: # Added for GitHub Actions PR problem 2020-12-19 -- remove later!
+          - os: windows-latest
+            python-version: 3.9
 
     steps:
     - uses: actions/checkout@v2
@@ -40,7 +43,7 @@ jobs:
       uses: actions/cache@v2
       with:
         path: .venv
-        key: ${{ runner.os }}-${{ hashFiles('poetry.lock') }}-${{ matrix.python-version }}
+        key: ${{ runner.os }}-${{ hashFiles('poetry.lock') }}-${{ matrix.python-version }}-v2
 
     - name: Install dependencies
       run: |
@@ -67,35 +70,3 @@ jobs:
     - name: Test with behave
       if: success() || failure()
       run: poetry run behave --no-skipped --format progress2 --junit --junit-directory reports/behave
-
-    - name: Upload Unit Test Results
-      if: success() || failure()
-      uses: actions/upload-artifact@v2
-      with:
-        name: Unit Test Results
-        path: reports/**/*.xml
-
-  publish-test-results:
-    if: success() || failure()
-    name: "Publish Unit Tests Results"
-    needs: test
-    runs-on: ubuntu-latest
-
-    steps:
-      - name: Download Artifacts
-        uses: actions/download-artifact@v2
-        with:
-          path: artifacts
-
-      - name: Publish Unit Test Results
-        uses: EnricoMi/publish-unit-test-result-action@v1.4
-        if: always()
-        with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          check_name: Unit Test Results
-          hide_comments: all but latest
-          comment_on_pr: true
-          files: '**/*.xml'
-          report_individual_runs: true
-          deduplicate_classes_by_file_name: false
-