Rename nightly pytest workflow

Changes:

* Use a leading underscore in the file name, because that seems to be
  more conventional in other repos using sub-workflows.

* Rename the run-name of the workflow itself to be more accurate and
  informational.

Author: mhucka

.github/workflows/nightly-pytest.yaml .github/workflows/_nightly-cirq-test.yaml.github/workflows/nightly-pytest.yaml renamed to .github/workflows/_nightly-cirq-test.yaml

@@ -17,8 +17,10 @@
 # This workflow expects input values passed by nightly.yml.
 # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-name: 'Nightly tests & scans – Pytest matrix'
-run-name: Run nightly Pytest
+# The tilde is only to make our sub-workflows be listed last in the GitHub UI.
+name: '~ Cirq version tests'
+run-name: >-
+  Run tests using the ${{inputs.cirq-release}} version of Cirq ${{inputs.reason}}
 
 on:
   workflow_call:
@@ -27,10 +29,14 @@ on:
       args:
         type: string
         required: false
-      # Why is this workflow being called?
+      # (For the job name) Why is this workflow being called?
       reason:
         type: string
         required: false
+      # (For the job name) What version of Cirq will be used?
+      cirq-release:
+        type: string
+        required: false
 
   # Allow manual invocation.
   workflow_dispatch:

.github/workflows/nightly.yaml

@@ -36,17 +36,19 @@ permissions: read-all
 jobs:
   cirq-stable:
     name: Nightly Pytest Cirq stable
-    uses: ./.github/workflows/nightly-pytest.yaml
+    uses: ./.github/workflows/_nightly-cirq-test.yaml
     with:
       args: ''
       reason: '(nightly)'
+      cirq-release: 'stable'
 
   cirq-pre:
     name: Nightly Pytest Cirq pre-release
-    uses: ./.github/workflows/nightly-pytest.yaml
+    uses: ./.github/workflows/_nightly-cirq-test.yaml
     with:
       args: '--pre'
       reason: '(nightly)'
+      cirq-release: 'pre-release'
 
   codeql:
     name: Nightly CodeQL code scan