PRE-M8-T02: add read-only WarmteLink serial probe

dev-requirements.txt

@@ -88,6 +88,8 @@ pyproject-hooks==1.2.0
     # via
     #   build
     #   pip-tools
+pyserial==3.5
+    # via -r requirements.in
 pytest==8.4.2
     # via -r dev-requirements.in
 python-dotenv==1.2.2