chore(ci): Speed up CI dependency installation

Cache pip downloads and install prebuilt psycopg wheels outside release
PRs, which keep the [c] build users install and always run the tests.
Also run the affected jobs when ci.yml or migration data changes, and
print Django's setup timings.

Fixes #23263

.github/workflows/ci.yml

@@ -39,6 +39,9 @@ jobs:
       python: ${{ steps.filter.outputs.python }}
       frontend: ${{ steps.filter.outputs.frontend }}
       docs: ${{ steps.filter.outputs.docs }}
+      # Release PRs (feature into main, or a release-vX.Y.Z branch) always run the test suite
+      # and install the [c] psycopg build users get.
+      release_pr: ${{ (github.head_ref == 'feature' && github.base_ref == 'main') || startsWith(github.head_ref, 'release-v') }}
     steps:
       - name: Check out repo
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
@@ -50,13 +53,17 @@ jobs:
           filters: |
             python:
               - 'netbox/**/*.py'
+              - 'netbox/**/migrations/**'
               - 'requirements*.txt'
               - 'pyproject.toml'
+              - '.github/workflows/ci.yml'
             frontend:
               - 'netbox/project-static/**'
+              - '.github/workflows/ci.yml'
             docs:
               - 'docs/**'
               - 'mkdocs.yml'
+              - '.github/workflows/ci.yml'
 
   lint:
     name: Lint (Python)
@@ -78,10 +85,13 @@ jobs:
     name: >-
       Tests (Python ${{ matrix.python-version }}${{ matrix.coverage && ', coverage' || '' }})
     needs: changes
-    if: needs.changes.result == 'success' && needs.changes.outputs.python == 'true'
+    if: >-
+      needs.changes.result == 'success'
+      && (needs.changes.outputs.python == 'true' || needs.changes.outputs.release_pr == 'true')
     runs-on: ubuntu-latest
     env:
       NETBOX_CONFIGURATION: netbox.configuration_testing
+      RELEASE_PR: ${{ needs.changes.outputs.release_pr }}
     strategy:
       matrix:
         python-version: ['3.12', '3.13', '3.14']
@@ -116,6 +126,22 @@ jobs:
         uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97  # v7.0.0
         with:
           python-version: ${{ matrix.python-version }}
+          cache: pip
+          cache-dependency-path: |
+            requirements.txt
+            .github/workflows/ci.yml
+
+      - name: Select the psycopg implementation
+        run: |
+          if [ "$RELEASE_PR" = true ]; then
+            echo "PSYCOPG_IMPL=c" >> "$GITHUB_ENV"
+          else
+            # Prebuilt wheels skip compiling against libpq.
+            sed -i 's/^psycopg\[c,pool\]==/psycopg[binary,pool]==/' requirements.txt
+            grep -q '^psycopg\[binary,pool\]==' requirements.txt \
+              || { echo "::error::requirements.txt no longer pins psycopg[c,pool]=="; exit 1; }
+            echo "PSYCOPG_IMPL=binary" >> "$GITHUB_ENV"
+          fi
 
       - name: Install dependencies
         run: |
@@ -133,11 +159,11 @@ jobs:
 
       - name: Run tests
         if: ${{ ! matrix.coverage }}
-        run: python netbox/manage.py test netbox/ --parallel
+        run: python netbox/manage.py test netbox/ --parallel --timing
 
       - name: Run tests with coverage
         if: ${{ matrix.coverage }}
-        run: coverage run netbox/manage.py test netbox/ --parallel
+        run: coverage run netbox/manage.py test netbox/ --parallel --timing
 
       - name: Combine coverage data
         if: ${{ matrix.coverage }}
@@ -196,9 +222,15 @@ jobs:
         uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97  # v7.0.0
         with:
           python-version: '3.12'
+          cache: pip
+          cache-dependency-path: |
+            requirements.txt
+            .github/workflows/ci.yml
 
       - name: Install dependencies
         run: |
+          # Shares the 3.12 test job's pip cache entry.
+          sed -i 's/^psycopg\[c,pool\]==/psycopg[binary,pool]==/' requirements.txt
           python -m pip install --upgrade pip
           pip install -r requirements.txt