Fix a non-POSIX shell redirection in entrypoints

Since we switched entrypoint shebangs from `/bin/bash` to `/bin/sh` (under the hood: `dash` on Debian, `ash` on Alpine) in d70ebaa, entrypoints must be POSIX compliant.

Unfortunately, the `&>` redirection is not POSIX-compliant and resulted in the left-hand command to be executed in background (without stdout/stdin redirection) because of the `&` character.

This commit uses a POSIX-compliant way to redirect both stdin and stdout to `/dev/null`.

Author: michaelbaudino

entrypoints/bundler-entrypoint

@@ -8,7 +8,7 @@ fi
 
 if [ -f Gemfile ]; then
   echo -n "Checking bundle... "
-  if bundle check &> /dev/null; then
+  if bundle check > /dev/null 2>&1; then
     echo "all good 👌"
   else
     echo "Something is missing 💥"

entrypoints/yarn-entrypoint

@@ -13,7 +13,7 @@ if [ -f package.json ]; then
       || echo "yarn check --integrity --verify-tree --silent" \
   )
   echo -n "Checking JS modules... "
-  if eval ${check_command} &> /dev/null; then
+  if eval ${check_command} > /dev/null 2>&1; then
     echo "all good 👌"
   else
     echo "something is missing 💥"