Preserve dash pattern on new page, fix #992

[gmischler]

Fixes #992

Checklist:

• The GitHub pipeline is OK (green),
  meaning that both pylint (static code analyzer) and black (code formatter) are happy with the changes of this PR.
• A unit test is covering the code added / modified by this PR
• This PR is ready to be merged
• [NA] In case of a new feature, docstrings have been added, with also some documentation in the docs/ folder
• A mention of the change is present in CHANGELOG.md

By submitting this pull request, I confirm that my contribution is made under the terms of the GNU LGPL 3.0 license.

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (fb9fd9c) 93.79% compared to head (377ec38) 93.79%.

❗ Current head 377ec38 differs from pull request most recent head e79cf54. Consider uploading reports for the commit e79cf54 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #993   +/-   ##
=======================================
  Coverage   93.79%   93.79%           
=======================================
  Files          28       28           
  Lines        8391     8396    +5     
  Branches     1544     1545    +1     
=======================================
+ Hits         7870     7875    +5     
  Misses        323      323           
  Partials      198      198           

Files	Coverage Δ
fpdf/fpdf.py	93.06% <100.00%> (+0.01%)	⬆️
fpdf/line_break.py	99.14% <100.00%> (ø)
fpdf/graphics_state.py	98.78% <80.00%> (ø)

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[Lucas-C]

Thank you and good job on this @gmischler 👍