Update GitHub workflow

Author: nadimkobeissi

.github/workflows/go.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Set up Go 1.x
       uses: actions/setup-go@v2
       with:
-        go-version: ^1.20
+        go-version: ^1.21
       id: go
 
     - name: Check out code into the Go module directory

go.mod

@@ -3,7 +3,7 @@
 
 module github.com/symbolicsoft/kyber-k2so
 
-go 1.20
+go 1.21
 
 require golang.org/x/crypto v0.16.0