Updated requirements to point to TACK repository

requirements.txt

@@ -10,4 +10,6 @@ pandas
 joblib
 torch
 lightning
-tackai  # install from the TACK package once published
+# Install tackai and all its dependencies from source.
+# hatchling build backend is PEP 517-compliant, so pip handles this fine.
+git+https://github.com/ribesstefano/TACK.git@main