Fix: (org-ql--def-query-string-to-sexp-fn) Updated for peg v1.0.1

Fixes #314, fixes #316.  Thanks to Akira Komamura (@akirak) and Joon
Ro (@joonro) for reporting.

Instead of `[blank]` in this PEX, it used to be `(syntax-class
whitespace)`, which worked fine with peg v1.0.  Then
<https://debbugs.gnu.org/cgi/bugreport.cgi?bug=59345> was filed and
resulted in the release of peg v1.0.1, after which that no longer
worked.  As best I can tell from reading the discussion, `[blank]` and
`(syntax-class whitespace)` should behave the same way, yet here they
do not: with peg v1.0.1, only `[blank]` works.  Why, I do not know; I
only tried it because I could find no explanation for the broken
behavior, and luckily, it works.  Maybe it's due to the use of
`(syntax-class whitespace)` later in the `pexs`; but since it finally
works again, let's take the victory as-is.

README.org

@@ -524,7 +524,8 @@ Simple links may also be written manually in either sexp or non-sexp form, like:
 
 ** 0.6.3-pre
 
-Nothing yet.
+*Fixed*
++ Non-sexp query parsing with updated version 1.0.1 of the ~peg~ package.  (Fixes [[https://github.com/alphapapa/org-ql/issues/314][#314]], [[https://github.com/alphapapa/org-ql/issues/316][#316]].  Thanks to [[https://github.com/akirak][Akira Komamura]] and [[https://github.com/joonro][Joon Ro]] for reporting.)
 
 ** 0.6.2