Use the correct token minting URL for TestPyPI

Author: AA-Turner

.github/workflows/create-release.yml

@@ -48,7 +48,7 @@ jobs:
             const oidc_token = (await oidc_resp.json()).value;
   
             // exchange the OIDC token for an API token
-            const mint_resp = await fetch('https://pypi.org/_/oidc/github/mint-token', {
+            const mint_resp = await fetch('https://test.pypi.org/_/oidc/github/mint-token', {
                 method: 'post',
                 body: '{"token": "oidc_token"}' ,
                 headers: {'Content-Type': 'application/json'},