Remove hardcoded VERSION constant

[hugovk]

To find the version, use:

try:
    # Python 3.8+
    import importlib.metadata as importlib_metadata
except ImportError:
    # Python 3.7
    import importlib_metadata


print(importlib_metadata.version("termcolor"))

Docs: https://docs.python.org/3/library/importlib.metadata.html#distribution-versions
Backport: https://pypi.org/project/importlib-metadata/

[codecov]

Codecov Report

Merging #18 (18ae230) into main (bde5a71) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main       #18   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines           70        69    -1     
=========================================
- Hits            70        69    -1     

Flag	Coverage Δ
macos-latest	100.00% <100.00%> (ø)
ubuntu-latest	100.00% <100.00%> (ø)
windows-latest	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/termcolor/termcolor.py	100.00% <ø> (ø)
src/termcolor/__init__.py	100.00% <100.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.