ENH: Use getfullargspec instead of deprecated getargspec

Use `getfullargspec` instead of deprecated `getargspec` to get the names
and default values of function parameters.

Fixes:
```
inspect. getargspec() is deprecated since Python 3.0,
 use inspect. signature() or inspect. getfullargspec()
```

reported by IDE inspection tool.

tract_querier/tract_math/decorator.py

@@ -100,7 +100,7 @@ def wrapper(*input_args):
             args, options_dict = find_optional_args(input_args)
 
             total_args = len(args)
-            argspec = inspect.getargspec(func)
+            argspec = inspect.getfullargspec(func)
             # Subtract 1 for implicit options_dict
             func_total_args = len(argspec.args) - 1