- fixes a small bug with detection_filter so that instance methods (#308)

should work...so hypothetically one could create a detection filter
  like:

```python
class DetectionFilter():

    def init(self, data):
        self.data = data

    def __call__(self, box, mask, logit, phrase, i):
        return phrase == self.data

sam.predict(..., detection_filter=DetectionFilter(data='mystring'))
```

Author: brendancol

samgeo/text_sam.py

@@ -257,7 +257,7 @@ def predict(
             save_args (dict, optional): Save arguments for the prediction. Defaults to {}.
             return_results (bool, optional): Whether to return the results. Defaults to False.
             detection_filter (callable, optional):
-                Callable which with box, mask, logit, phrase, and index args returns a boolean.
+                Callable with box, mask, logit, phrase, and index args returns a boolean.
                 If provided, the function will be called for each detected object.
                 Defaults to None.
 
@@ -325,8 +325,7 @@ def predict(
                 if not callable(detection_filter):
                     raise ValueError("detection_filter must be callable.")
 
-                req_nargs = 6 if inspect.ismethod(detection_filter) else 5
-                if not len(inspect.signature(detection_filter).parameters) == req_nargs:
+                if not len(inspect.signature(detection_filter).parameters) == 5:
                     raise ValueError(
                         "detection_filter required args: "
                         "box, mask, logit, phrase, and index."