ci(shellcheck): check all shell scripts recursively (#436)

run-tests.sh

@@ -9,18 +9,14 @@
 set -o errexit
 set -o nounset
 
-check_shellcheck () {
-    shellcheck run-tests.sh
-}
-
 check_commitlint () {
     from=${2:-master}
     to=${3:-HEAD}
-    npx commitlint --from="$from" --to="$to" --verbose
+    npx commitlint --from="$from" --to="$to"
     found=0
     while IFS= read -r line; do
         if echo "$line" | grep -qP "\(\#[0-9]+\)$"; then
-            echo "✔   PR number present in $line"
+            true
         else
             echo "✖   PR number missing in $line"
             found=1
@@ -31,6 +27,10 @@ check_commitlint () {
     fi
 }
 
+check_shellcheck () {
+    find . -name "*.sh" -exec shellcheck {} \;
+}
+
 check_pydocstyle () {
     pydocstyle reana_commons
 }