Bug fix for parameter i/o and checks

[KMarkert]

This pull request fixes a few bugs that were occurring with parsing/checking routing information or writing data out. Specific changes:

• rvic/parameters.py: updated pour point parsing to use pandas v1+ API
• setup.py: added pandas v1+ as dependency
• rvic/core/utilities.py: fixed bug trying to access .max() method on scalar floats
• rvic/core/utilities.py: squeezed output char_names when writing to file

Tests were run on the samples/configs/rvic.parameters.rasm.cfg using rvic parameter and samples/configs/rvic.convolution.rasm.cfg using rvic convolution.