Remove Python 2.7 from performance tests

- seems to be unreliable, and is obsolete anyway

Author: mrbean-bremen

.github/workflows/performance.yml

@@ -14,7 +14,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        python-version: [2.7, 3.6, 3.9]
+        python-version: [3.6, 3.9]
     env:
       OS: ${{ matrix.os }}
     steps: