remove 1.20 from doctests

Author: ndyakov

.github/workflows/doctests.yaml

@@ -25,7 +25,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        go-version: [ "1.20", "1.21", "1.22", "1.23" ]
+        go-version: [ "1.21", "1.22", "1.23" ]
 
     steps:
       - name: Set up ${{ matrix.go-version }}