Fixup PyPI publish URL

```
25hERROR    RedirectDetected: https://pypi.org/project/viscm attempted to redirect 
         to https://pypi.org/project/viscm/.                                    
         Your repository URL is missing a trailing slash. Please add it and try 
         again.                          
```

Author: mfisher87

.github/workflows/release.yml

@@ -26,4 +26,4 @@ jobs:
         uses: "pypa/gh-action-pypi-publish@release/v1"
         with:
           password: "${{ secrets.PYPI_TOKEN }}"
-          repository-url: "https://pypi.org/project/viscm"
+          repository-url: "https://pypi.org/project/viscm/"