Update snap to github releases and snap store.

.github/workflows/snap.yml

@@ -26,9 +26,20 @@ jobs:
                 echo "version=$(echo ${{github.ref_name}} | cut -c2-)" >> $GITHUB_OUTPUT
             fi
       - uses: snapcore/action-build@v1
-        id: snapcraft
+        id: build
       - name: Upload artifact
         uses: actions/upload-artifact@v3
         with:
           name: sdrangel-${{ steps.get_version.outputs.version }}-amd64.snap
-          path: ${{ steps.snapcraft.outputs.snap }}
+          path: ${{ steps.build.outputs.snap }}
+      - name: Upload release
+        if: startsWith(github.ref, 'refs/tags/')
+        uses: softprops/action-gh-release@v2
+        with:
+          files: ${{ steps.build.outputs.snap }}
+      - uses: snapcore/action-publish@v1
+        env:
+          SNAPCRAFT_STORE_CREDENTIALS: ${{ secrets.SNAP_STORE_LOGIN }}
+        with:
+          snap: ${{ steps.build.outputs.snap }}
+          release: stable