Add stub for nightly release job

I cannot iterate in CI using the gh CLI unless a workflow already exists
in the main branch.

Same issue as seen in this stack overflow
https://stackoverflow.com/questions/74898693/gh-workflow-run-not-working-for-particular-branch

Add a placeholder stub. This workflow does not publish anything so it
should be safe to land without review.

Author: jhamon

.github/workflows/nightly-release.yaml

@@ -0,0 +1,17 @@
+name: 'PyPI Release: Nightly (pinecone-client-nightly)'
+
+on:
+  workflow_dispatch:
+
+jobs:
+  run-tests:
+    uses: './.github/workflows/testing.yaml'
+
+  pypi-nightly:
+    needs: run-tests
+    timeout-minutes: 30
+    name: pypi-nightly
+    runs-on: ubuntu-latest
+    steps:
+      - name: greeting
+        run: echo "Hello World"