Merge pull request #8023 from aabadie/pr/fix_static_test_squashing

dist/tools/pr_check: fix regex pattern to recognize any SHA

dist/tools/pr_check/pr_check.sh

@@ -25,7 +25,7 @@ else
 fi
 
 SQUASH_COMMITS="$(git log $(git merge-base HEAD "${RIOT_MASTER}")...HEAD --pretty=format:"    %h %s" | \
-                  grep -i -e "^    [0-9a-f]\{7\} .\{0,2\}SQUASH" -e "^    [0-9a-f]\{7\} .\{0,2\}FIX")"
+                  grep -i -e "^    [0-9a-f]\+ .\{0,2\}SQUASH" -e "^    [0-9a-f]\+ .\{0,2\}FIX")"
 
 if [ -n "${SQUASH_COMMITS}" ]; then
     echo -e "${CERROR}Pull request needs squashing:${CRESET}" 1>&2