adjust workflow to only run if version changes

.github/workflows/build_and_release.yml

@@ -6,8 +6,33 @@ on:
       - master
 
 jobs:
+  check_for_changed_version:
+    runs-on: 'ubuntu-latest'
+    # Declare outputs for next jobs
+    outputs:
+      version_changed: ${{ steps.check_file_changed.outputs.version_changed }}
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        # Checkout as many commits as needed for the diff
+        fetch-depth: 2
+    - id: check_file_changed
+      run: |
+        # Diff HEAD with the previous commit
+        if git diff HEAD^ HEAD pyproject.toml | grep -q "+version =";
+        then
+          GOTIME="True"
+        else
+          GOTIME="False"
+        fi
+        echo "::notice title=GOTIME::$GOTIME"
+        # Set the output named "version_changed"
+        echo "version_changed=$GOTIME" >> $GITHUB_OUTPUT
+  
   build:
     runs-on: ubuntu-latest
+    needs: [ check_for_changed_version ]
+    if: needs.check_for_changed_version.outputs.version_changed == 'True'
     permissions:
       contents: write
     steps:
@@ -21,19 +46,19 @@ jobs:
         pip install --upgrade pip
         pip install shiv
         pip install poetry
-    - name: Add CURRENT_TIME env property
-      run: echo "CURRENT_TIME_VERSION=v$(date '+%s')" >> $GITHUB_ENV
+    - name: Add VERSION env property
+      run: echo "VERSION=v$(poetry version | python -c 'import sys;print(sys.stdin.read().split()[1])')" >> $GITHUB_ENV
     - name: Build the sucker
       run: |
-        sed -i -e "s/?????/${{ env.CURRENT_TIME_VERSION }}/g" src/__init__.py
+        sed -i -e "s/?????/${{ env.VERSION }}/g" src/__init__.py
         make build
     - name: Create release!
       run: |
         JSON_DATA=$(
           printf '%s' \
           '{'\
-            '"tag_name":"${{ env.CURRENT_TIME_VERSION }}",'\
-            '"name":"${{ env.CURRENT_TIME_VERSION }}",'\
+            '"tag_name":"${{ env.VERSION }}",'\
+            '"name":"${{ env.VERSION }}",'\
             '"body":"RELEASE THE KRAKEN"'\
           '}' \
         )