Updates example/layout.py to use Splitter class

[apoclyps]

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

Resolves a TypeError when running examples/layout.py using rich=10.0.0.

What's Changed

Whilst upgrading from 9.13.0 to 10.0.0 within my application I encountered a breaking changed related to direction being removed and replaced with the new Splitter class as outlined in the changelog.

Upon inspecting the source and running the example I noticed it had not been updated to reflect the latest changes.

This PR removes the unused Direction literal and updates example/layout.py to use split_row instead of direction="horizontal" to help others quickly identify the necessary change.

Steps to reproduce

Run examples/layout.py using rich==10.0.0 to produce the following TypeError:

Traceback (most recent call last):
  File "/home/host/workspace/apoclyps/rich/examples/layout.py", line 26, in <module>
    layout["main"].split(
TypeError: split() got an unexpected keyword argument 'direction'

[codecov]

Codecov Report

Merging #1142 (f24b668) into master (34c5620) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1142      +/-   ##
==========================================
- Coverage   99.84%   99.84%   -0.01%     
==========================================
  Files          69       69              
  Lines        6323     6322       -1     
==========================================
- Hits         6313     6312       -1     
  Misses         10       10              

Flag	Coverage Δ
unittests	99.84% <100.00%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
rich/layout.py	100.00% <ø> (ø)
rich/segment.py	100.00% <ø> (ø)
rich/constrain.py	100.00% <100.00%> (ø)
rich/repr.py	100.00% <100.00%> (ø)
rich/theme.py	100.00% <100.00%> (ø)

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[willmcgugan]

Great. Thanks.