apply shellcheck review

Author: Kleidukos

.githooks/pre-push

@@ -8,13 +8,13 @@ else
 fi
 
 if which fourmolu > /dev/null ; then
-  find Cabal Cabal-syntax cabal-install -name '*.hs' \
+  find Cabal Cabal-syntax cabal-install -name '*.hs' -print0 \
     ! -path Cabal-syntax/src/Distribution/Fields/Lexer.hs \
     ! -path Cabal-syntax/src/Distribution/SPDX/LicenseExceptionId.hs \
     ! -path Cabal-syntax/src/Distribution/SPDX/LicenseId.hs \
     ! -path Cabal/src/Distribution/Simple/Build/Macros/Z.hs \
     ! -path Cabal/src/Distribution/Simple/Build/PathsModule/Z.hs \
-    | xargs -P ${PROCS} -I {} fourmolu -q --mode check {}
+    | xargs -P "${PROCS}" -I {} fourmolu -q --mode check {}
 else
   echo "Fourmolu not found, aborting."
   exit 1