requirements.txt basemap version

There is a problem with basemap package.
 If you check https://pypi.org/project/basemap/#history version 1.2.1 does not exist.
```
ERROR: Could not find a version that satisfies the requirement basemap==1.2.1 (from versions: 1.3.0b1, 1.3.0rc1, 1.3.0, 1.3.1, 1.3.2, 1.3.3, 1.3.4, 1.3.5, 1.3.6, 1.3.7)
ERROR: No matching distribution found for basemap==1.2.1
```