Use go 1.18 when setting up environment

Without this this command was failing with the following output:

```
[2023-08-09 17:01:25] + /tmp/golang_installer
[2023-08-09 17:01:25] Welcome to the Go installer!
[2023-08-09 17:01:26] Downloading Go version go1.21.0
[2023-08-09 17:01:26] time 2023-08-04T20:14:06Z to /root/.go
[2023-08-09 17:01:26] This may take a bit of time...
[2023-08-09 17:01:26] Downloading Go from 400 Bad Request failed with HTTP status %!s(MISSING)
```

hack/setup_env.sh

@@ -19,7 +19,7 @@ function golang() {
   echo "Installing golang..."
   curl --retry 5 --connect-timeout 30 -L https://storage.googleapis.com/golang/getgo/installer_linux -o /tmp/golang_installer
   chmod u+x /tmp/golang_installer
-  /tmp/golang_installer
+  /tmp/golang_installer -version 1.18
   rm /tmp/golang_installer
 
   echo "Activating go command on current shell..."