add source version check

Author: FynnBe

.github/workflows/build.yaml

@@ -280,6 +280,11 @@ jobs:
               valid = existing_tag.count("v") == 1 and existing_tag.count(".") == 2 and all(part.isdigit() for part in existing_tag.lstrip("v").split("."))
               if not valid:
                   raise Exception(f"Current commit has invalid version tag {existing_tag}.")
+
+              source_version = Path('src/bioimageio/core/__init__.py').read_text().split('__version__ = \"')[1].split('\"')[0]
+              if existing_tag != f"v{source_version}":
+                  raise Exception(f"Version tag {existing_tag} does not match source version {source_version}.")
+
               new_version = existing_tag
           else:
               new_version = "${{ steps.tag-version.outputs.tag }}"