Semaphore CI: apparently go 1.20 does not support toolchain directive

Author: codesenberg

.semaphore/semaphore.yml

@@ -12,10 +12,6 @@ blocks:
           - checkout
           - go install gotest.tools/gotestsum@latest
       jobs:
-        - name: Test go 1.20
-          commands:
-            - sem-version go 1.20
-            - gotestsum --junitfile report.xml ./...
         - name: Test go 1.21
           commands:
             - sem-version go 1.21