change pprint-str to print-str

[kbaba1001]

Because the error messages is only string, I think print-str looks better than pprint-str.
For example, when an error message has \n :

user=> (clojure.pprint/pprint "aaa\nbbb")
"aaa\nbbb"
nil
user=> (print "aaa\nbbb")
aaa
bbbnil

"aaa\nbbb" has raw \n instead of newline, but I'd like to show newline on messages.

[totakke]

Thank you for the PR.

The concept of cruler is a validation framework for non-programmers as well as programmers, so human-readable error texts formatted by pprint-str are mandatory.

When a Clojure data structure supplied to error-value is complicated, an error text generated by print-str is so difficult to read.

dev-resources/sample-validator/approved-drug/test.yml
  error: Should be distincted: :drug
    [{:drug foo, :types [{:category A, :serial 1234}], :comment A1} {:drug bar, :types [{:serial 9876}], :comment A2} {:drug bar, :types [{:serial 9876}], :comment A2}] ...
  line: unknown

pprint-str formats such a data structure.

dev-resources/sample-validator/approved-drug/test.yml
  error: Should be distincted: :drug
    [{:drug "foo", :types [{:category "A", :serial 1234}], :comment "A1"}
     {:drug "bar", :types [{:serial 9876}], :comment "A2"}
     {:drug "bar", :types [{:serial 9876}], :comment "A2"}]
     ...
  line: unknown

If you want to use the former error text generated by print-str, I suggest adding a formatting config like :format {:error-value :print} (default :pprint) to cruler.edn and switching an output process regarding to the config.

[kbaba1001]

@totakke Thank you for the review. I defined :format {:error-value :print} in cruler.edn. Could you check it out, please?

[totakke]

LGTM. Thank you.