(fix/deps): use rootDir: './src' instead of './'

- because './src' is actually being used as the rootDir

(deps): I deprecated this buggy option in TSDX but my PR has yet to be
released
- it outputs a warning in newer versions but no harm and only benefit
  in upgrading earlier

Author: agilgur5

tsconfig.json

@@ -6,7 +6,7 @@
     "importHelpers": true,
     "declaration": true,
     "sourceMap": true,
-    "rootDir": "./",
+    "rootDir": "./src",
     "strict": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,