lint: Increase max-module-lines to 3000 (GenericMappingTools#805)

We have these linting issues because base_plotting.py is too long:

```
pygmt/base_plotting.py:1:0: C0302: Too many lines in module (2047/2000) (too-many-lines)
```

The problem will be fixed in GenericMappingTools#685, but it may take some time.
This PR increases the max-module-lines to 3000 to temporarily disable the warning.

.pylintrc

@@ -293,7 +293,7 @@ indent-string='    '
 max-line-length=100
 
 # Maximum number of lines in a module.
-max-module-lines=2000
+max-module-lines=3000
 
 # List of optional constructs for which whitespace checking is disabled. `dict-
 # separator` is used to allow tabulation in dicts, etc.: {1  : 1,\n222: 2}.