Fix checksum command to strictly follow the required format + remove quiet option not support in BusyBox implementation (#46)

Author: nikita-tkachenko-datadog

action.yml

@@ -125,11 +125,11 @@ runs:
         fi
 
         if command -v sha256sum >/dev/null 2>&1; then
-          if ! echo "$INSTALLATION_SCRIPT_CHECKSUM $script_filepath" | sha256sum --quiet -c -; then
+          if ! echo "$INSTALLATION_SCRIPT_CHECKSUM  $script_filepath" | sha256sum -c -; then
             exit 1
           fi
         elif command -v shasum >/dev/null 2>&1; then
-          if ! echo "$INSTALLATION_SCRIPT_CHECKSUM  $script_filepath" | shasum --quiet -a 256 -c -; then
+          if ! echo "$INSTALLATION_SCRIPT_CHECKSUM  $script_filepath" | shasum -a 256 -c -; then
             exit 1
           fi
         else