fix(action)!: Fix preserve-block-position default (#393)

Current logic adds `--preserve-block-position` to list of args if the
length of the value provided to the `preserve-block-position` github
actions variable is not zero. Since it defaults to the string `false`,
this effectively defaults it to true. You can only disable it by setting
it explicitly to an empty string. This PR corrects this logic by only
enabling `preserve-block-position` if it's explicitly set to true.

BREAKING CHANGE: Effectively change default value for
preserve-block-position in github actions

action.yml

@@ -62,7 +62,7 @@ runs:
           ARGS_INPUT+=("--check")
         fi
 
-        if [ ! -z "${{inputs.preserve-block-position}}" ]; then
+        if [ "${{inputs.preserve-block-position}}" = "true" ]; then
           ARGS_INPUT+=("--preserve-block-position")
         fi