Switch to env var for input

entrypoint.sh

@@ -1,7 +1,7 @@
 #!/bin/sh -l
 
 # Use INPUT_<INPUT_NAME> to get the value of an input
-GREETING="Hello, $1!"
+GREETING="Hello, $INPUT_WHO_TO_GREET!"
 
 # Use workflow commands to do things like set debug messages
 echo "::notice file=entrypoint.sh,line=7::$GREETING"