🐛 pros upload crashes without helpful error when --slot is not given

[zabackary]

Describe the bug
pros upload crashes when a slot is missing instead of emitting an error.

To Reproduce

1. Run `pros upload --target v5 {path to file}"
2. pros crashes with "unsupported operand type" since the slot is a NoneType (i.e., undefined/None)

Expected behavior
PROS outputs an error similar to the text "Specify a slot to upload to."

Screenshots

$ pros upload --target v5 /dev/null
ERROR - __main__:main - unsupported operand type(s) for -=: 'NoneType' and 'int' - pros-cli version:3.5.0
  File "click\core.py", line 783, in invoke
  File "pros\cli\upload.py", line 121, in upload
TypeError: unsupported operand type(s) for -=: 'NoneType' and 'int'

Here's the permalink to the line in question:

pros-cli/pros/cli/upload.py

Line 121 in 30dfe91

kwargs['slot'] -= 1

PROS version:
3.5.0

Desktop (please complete the following information):

• OS: Windows 10
• Version 22H2 (OS build 19045.4046)

Other context:
I'm trying out pros-rs (Rust bindings to the PROS libraries) to generate the binary, but that probably doesn't matter.

I'm new to PROS and my team likely won't let me switch because I just convinced them this year to use VEXCode Python since CPP is a little tricky for beginners, but if you would like, I can submit a PR sometime next weekend.

[zabackary]

Oops, just realized this is a duplicate of #245. Sorry for the noise.