fix: indentation rules for script and style tags

[FlorentinBouchendhomme]

Issue Addressed

Fixes #264

Summary

Add the missing handling inside the file indent.js to manage the closing tags for script and style

Tests

Two tests added inside indent.test.js to verify:

• if a valid </script> tag and </style> tag passes without errors
• if an invalid </script> tag and </style> tag (with incorrect indentation e.g. two extra spaces) triggers errors

[yeonjuan]

@FlorentinBouchendhomme Thanks for the fix! LGTM 👍