Fix Serverless v4 check in run script (#12030)

run

@@ -32,9 +32,10 @@ if ! which yarn > /dev/null ; then
 fi
 
 # check serverless is installed globally.
-if ! which serverless > /dev/null || [[ "$(serverless --version | cut -d'.' -f1)" != "4" ]]; then
+if ! which serverless > /dev/null || ! serverless --version 2>&1 | grep -q " 4."; then
     echo "installing serverless v4 globally"
     yarn global add [email protected]
+    export PATH="$PATH:$(yarn global bin)"
 fi
 
 # have to ensure that yarn install is up to date.