build: enable unconvert linter (#15456)

* build: enable unconvert linter

 - fixes #15453
 - update code base for failing cases

* cmd/puppeth: replace syscall.Stdin with os.Stdin.Fd() for unconvert linter

core/vm/interpreter.go

@@ -161,8 +161,8 @@ func (in *Interpreter) Run(snapshot int, contract *Contract, input []byte) (ret
 
 		if in.cfg.Debug {
 			logged = false
-			pcCopy = uint64(pc)
-			gasCopy = uint64(contract.Gas)
+			pcCopy = pc
+			gasCopy = contract.Gas
 			stackCopy = newstack()
 			for _, val := range stack.data {
 				stackCopy.push(val)