Arch Linux

Description:
Package calcurse [1] optionally depends on package python-pyparsing [2] for CalDAV support. This optional dependency is currently missing.

Additional info:
* calcurse 4.7.1-1
* python-pyparsing 2.4.7-3

Steps to reproduce:

1.
Have calcurse and optional dependencies python and python-httplib2 installed, and python-pyparsing not installed.

2.
Run `calcurse-caldav`.

3.
Observe the following output:

```
$ calcurse-caldav
Traceback (most recent call last):
File "/usr/bin/calcurse-caldav", line 14, in <module>
import httplib2
File "/usr/lib/python3.9/site-packages/httplib2/__init__.py", line 52, in <module>
from . import auth
File "/usr/lib/python3.9/site-packages/httplib2/auth.py", line 4, in <module>
import pyparsing as pp
ModuleNotFoundError: No module named 'pyparsing'
```

Suggested solution:
Add python-pyparsing as an optional dependency to calcurse.


[1]
https://archlinux.org/packages/community/x86_64/calcurse/

[2]
https://archlinux.org/packages/extra/any/python-pyparsing/