Revert "forbid building with go1.20 or newer"

This reverts commit 50cd051.

cmd/opera/main.go

@@ -3,22 +3,11 @@ package main
 import (
 	"fmt"
 	"os"
-	"runtime"
 
 	"github.com/Fantom-foundation/go-opera/cmd/opera/launcher"
 )
 
 func main() {
-	// TODO erase after compatibility issues with go1.20 are fixed
-	var majorVer int
-	var minorVer int
-	var other string
-	n, err := fmt.Sscanf(runtime.Version(), "go%d.%d%s", &majorVer, &minorVer, &other)
-	if n >= 2 && err == nil {
-		if (majorVer*100 + minorVer) > 119 {
-			panic(runtime.Version() + " is not supported, please downgrade your go compiler to go 1.19 or older")
-		}
-	}
 	if err := launcher.Launch(os.Args); err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)