Render height fix

[darrenburns]

Type of changes

• Bug fix
• New feature
• Documentation / docstrings
• Tests
• Other

Checklist

• I've run the latest black with default args on new code.
• I've updated CHANGELOG.md and CONTRIBUTORS.md where appropriate.
• I've added tests for new code.
• I accept that @willmcgugan may be pedantic in the code review.

Description

Fixes the following example:

    from rich.console import Console
    from rich.padding import Padding

    console = Console()
    options = console.options.update_height(1)

    padding = Padding("hello", pad=(1, 1, 1, 1))
    console.render_lines(padding, options=options)

The height is ending up negative when specified as 1, because we subtract the vertical padding from it (1-2 = -1). It gets passed to itertools.islice in render_lines as the "stop" argument, and that bombs out.

[codecov-commenter]

Codecov Report

Merging #2246 (8d8532d) into master (14d47c9) will decrease coverage by 0.08%.
The diff coverage is 95.91%.

@@            Coverage Diff             @@
##           master    #2246      +/-   ##
==========================================
- Coverage   98.88%   98.79%   -0.09%     
==========================================
  Files          73       73              
  Lines        7629     7659      +30     
==========================================
+ Hits         7544     7567      +23     
- Misses         85       92       +7     

Flag	Coverage Δ
unittests	98.79% <95.91%> (-0.09%)	⬇️

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

Impacted Files	Coverage Δ
rich/_export_format.py	100.00% <ø> (ø)
rich/console.py	98.28% <95.87%> (-0.50%)	⬇️
rich/terminal_theme.py	100.00% <100.00%> (ø)
rich/traceback.py	98.68% <0.00%> (-0.88%)	⬇️

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