Update _colors.py

fix error message to include "." so the command works

Author: dhkts1

mypy_baseline/_colors.py

@@ -20,7 +20,7 @@
 FIXED_ERRORS = """
     ┌────────────────────────────────────────────┄┄
     │ {green}Your changes resolved existing violations.{end}
-    │ Great work! Please, run `mypy | mypy-baseline sync`
+    │ Great work! Please, run `mypy . | mypy-baseline sync`
     │ to remove resolved violations from the baseline file.
     └────────────────────────────────────────────┄┄
 """