Removing the vertical examples support

[olegpidsadnyi]

Part of the project of gherking 6 compatibility. Vertical examples are not supported by gherkin.
The gherkin examples can have names like

Examples: Foo bar baz or even Examples: Vertical which is also a name clash.

[codecov]

Codecov Report

Merging #492 (1d65460) into master (e0a1437) will decrease coverage by 0.74%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #492      +/-   ##
==========================================
- Coverage   95.86%   95.12%   -0.75%     
==========================================
  Files          49       49              
  Lines        1621     1579      -42     
  Branches      177      171       -6     
==========================================
- Hits         1554     1502      -52     
- Misses         41       48       +7     
- Partials       26       29       +3     

Impacted Files	Coverage Δ
pytest_bdd/parser.py	97.97% <0.00%> (-1.56%)	⬇️
pytest_bdd/types.py	100.00% <ø> (ø)
tests/feature/test_outline.py	100.00% <ø> (ø)
tests/feature/test_outline_empty_values.py	100.00% <ø> (ø)
tests/utils.py	66.66% <0.00%> (-33.34%)	⬇️
tests/conftest.py	77.77% <0.00%> (-22.23%)	⬇️
tests/feature/test_tags.py	96.15% <0.00%> (-3.85%)	⬇️

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