The problem with printing the exception was that starting with
Python 3.6 the ImportError is yet another (sub) exception called
ModuleNotFoundError which can't be printed as a string and then triggers
another exception:
```
Traceback (most recent call last):
File "/home/julianoes/src/Firmware/Tools/serial/generate_config.py", line 11, in <module>
import jinja2
ModuleNotFoundError: No module named 'jinja2'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/julianoes/src/Firmware/Tools/serial/generate_config.py", line 13, in <module>
print("Failed to import jinja2: " + e)
TypeError: must be str, not ModuleNotFoundError
```
As per @bkueng's suggestion the easiest is to cast the exception to str
and that way prevent the second exception.
