Remove colons from log rotation file name(extension).

[sushichop]

This PR fixes #10 with small change.

[github-actions]

	1 Warning
⚠️	The library files were changed, but the tests remained unmodified. Consider updating or adding to the tests to match the library changes.

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[codecov]

Codecov Report

Merging #11 (038c82f) into main (a19c3dc) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main      #11   +/-   ##
=======================================
  Coverage   97.73%   97.73%           
=======================================
  Files          10       10           
  Lines         398      398           
=======================================
  Hits          389      389           
  Misses          9        9           

Impacted Files	Coverage Δ
Sources/Puppy/FileRotationLogger.swift	94.38% <100.00%> (ø)

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