chore: publish with attestation (#36)

Based on [attestation warnings in the release
pipeline](https://github.com/equinix/equinix-sdk-python/actions/runs/12290045589),
this PR removes the username and password combo, as advised in the GHA
warnings and here:
https://github.com/pypa/gh-action-pypi-publish?tab=readme-ov-file#trusted-publishing

I've added the Trusted Publisher Management publisher profile for GitHub
to the Pypi project.
https://pypi.org/manage/project/equinix/settings/publishing/

I'm leaving the token credential in GHA Secrets, for now, so that we can
revert this PR and take the alternate approach of disabling attestation
if there are additional hurdles in the publishing phase.

.github/workflows/release.yaml

@@ -11,6 +11,8 @@ jobs:
   release:
     name: Build and publish package
     runs-on: ubuntu-latest
+    permissions:
+      id-token: write 
 
     steps:
       - name: Checkout
@@ -51,6 +53,4 @@ jobs:
       - name: Publish package
         uses: pypa/gh-action-pypi-publish@release/v1
         with:
-          user: __token__
-          password: ${{ secrets.PYPI_API_TOKEN }}
           packages-dir: ${{ env.DIST_DIR }}