Error for more than one file with -c

[aabiddanda]

Addresses plan of action for #63. Main additions are:

1. Error message if using -c flag for compression and more than one input file.
2. Test to verify that error message is being thrown.

Comments & suggestions for error throwing/exiting messages are welcome (I opted for exit as its handled at the CLI-level).

[codecov-commenter]

Codecov Report

Merging #64 (a54ac13) into main (73fe8a0) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head a54ac13 differs from pull request most recent head 95dd4ed. Consider uploading reports for the commit 95dd4ed to get more accurate results

@@            Coverage Diff             @@
##             main      #64      +/-   ##
==========================================
+ Coverage   97.56%   97.58%   +0.01%     
==========================================
  Files           6        6              
  Lines         329      331       +2     
  Branches       65       66       +1     
==========================================
+ Hits          321      323       +2     
  Misses          6        6              
  Partials        2        2              

Impacted Files	Coverage Δ
tszip/cli.py	99.06% <100.00%> (+0.01%)	⬆️

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[jeromekelleher]

This is perfect @aabiddanda - as you say, we're doing this at the CLI level, so exit() is the right option.

If could update the CHANGELOG as well we can close #62 and we're ready to release I think.

[aabiddanda]

Awesome - this should have the changelog amended and the erroneous line removed. All boiled down to a nice squashed commit.

[jeromekelleher]

LGTM! I'll ship the release immediately