relax menopdetect dependency

We are having issues getting menpodetect 0.4.1+ built on some platforms.

0.4.1 only fixes deprecation warnings from menpo changes, so for now on
some macOS/Windows builds users of LSFM may see deprecation warnings. We
can live with that for now...

conda/meta.yaml

@@ -18,7 +18,7 @@ requirements:
     - python
     - menpo3d >=0.5.0,<0.6
     - menpofit >=0.4.1,<0.5
-    - menpodetect >=0.4.1,<0.5
+    - menpodetect 0.4.*
     - joblib >=0.9.4
     - docopt >=0.6.2