test(NODE-4322): unskip other test

Author: durran

test/integration/sessions/sessions.spec.test.ts

@@ -2,8 +2,5 @@ import { loadSpecTests } from '../../spec';
 import { runUnifiedSuite } from '../../tools/unified-spec-runner/runner';
 
 describe('Sessions spec tests', function () {
-  runUnifiedSuite(loadSpecTests('sessions'), [
-    // TODO(NODE-3951): fix broken dirty sessions spec tests
-    'Dirty explicit session is discarded (findAndModify)'
-  ]);
+  runUnifiedSuite(loadSpecTests('sessions'));
 });