Add dedicated codspeed GitHub action

And disable running benchmarks on appveyor.

Appveyor is not supported by codspeed, and there is no values in running
benchmarks without doing anything with the results.

.appveyor.yml

@@ -303,7 +303,7 @@ for:
       # run tests on installed module, not source tree files
       - |
         cd __testhome__
-        python -m pytest -s -v --durations 20 -m "not (turtle)" -k "$KEYWORDS" --cov=datalad_next --cov datalad --cov-config=../.coveragerc --pyargs ${DTS}
+        python -m pytest -s -v --durations 20 -m "not (turtle)" -k "$KEYWORDS" --cov=datalad_next --cov datalad --cov-config=../.coveragerc --benchmark-disable --pyargs ${DTS}
 
     after_test:
       - python -m coverage xml
@@ -370,7 +370,7 @@ for:
       - cmd: md __testhome__
       - cmd: cd __testhome__
         # run test selecion (--traverse-namespace needed from Python 3.8 onwards)
-      - cmd: python -m pytest -s -v --durations 20 -m "not (turtle)" -k "%KEYWORDS%" --cov=datalad_next --cov-config=..\.coveragerc --pyargs %DTS%
+      - cmd: python -m pytest -s -v --durations 20 -m "not (turtle)" -k "%KEYWORDS%" --cov=datalad_next --cov-config=..\.coveragerc --benchmark-disable --pyargs %DTS%
 
     after_test:
       - cmd: python -m coverage xml

.github/workflows/codspeed.yml

@@ -0,0 +1,44 @@
+name: codspeed-benchmarks
+
+on:
+  # Run on pushes to the main branch
+  push:
+    branches:
+      - "main"
+  # Run on pull requests
+  pull_request:
+  # `workflow_dispatch` allows CodSpeed to trigger backtest
+  # performance analysis in order to generate initial data.
+  workflow_dispatch:
+
+jobs:
+  benchmarks:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup Python
+        uses: actions/setup-python@v4
+        with:
+          # codspeed needs 3.12 for trace generation
+          python-version: 3.12
+      - name: Set up environment
+        run: |
+          git config --global user.email "[email protected]"
+          git config --global user.name "GitHub Almighty"
+      - name: Upgrade pip
+        run: python -m pip install --upgrade pip
+      - name: Install git-annex
+        run: |
+          python -m pip install datalad-installer
+          datalad-installer -E ${HOME}/dlinstaller_env.sh --sudo ok git-annex -m snapshot
+      - name: Install dependencies
+        run: |
+          python -m pip install -r requirements-devel.txt
+          python -m pip install pytest-codspeed
+      - name: Run benchmarks
+        uses: CodSpeedHQ/action@v2
+        with:
+          token: ${{ secrets.CODSPEED_TOKEN }}
+          run: |
+            . ${HOME}/dlinstaller_env.sh
+            python -m pytest --codspeed datalad_next