fix: allow % and } in {%p %}/{%tr %}/{%tc %}/{%r %} expressions

[Noethix55555]

Fixes #644.

patch_xml matched the expression body of these directive tags with [^}%]*, which stops at the first % or }. Tags whose expression contains a modulo (if i % 2 == 0) or a literal brace (set d = {"x":1}) were not stripped of their surrounding <w:p>/<w:tr>/<w:tc>/<w:r> wrapper, so the literal {%p ...%} reached Jinja and raised TemplateSyntaxError: Encountered unknown tag 'p'.

The fix matches up to the closing %}/}} instead of excluding those characters:

([^}%%]*(?:%%}|}}))  ->  ((?:(?!%%}|}}).)*(?:%%}|}}))

Verified with a real render: a template using {%p if i % 2 == 0 %} raises TemplateSyntaxError on the current code and renders correctly with the fix. The representative existing fixture tests (dynamic_table, nested_for, vertical_merge, horizontal_merge, less_cells_after_loop, comments, escape, merge_paragraph, richtext, order and others) still pass.

CI runs flake8 only and the existing tests are binary .docx fixtures with no assertions, so I did not add a fixture; the reproduction above is in the linked issue. Happy to add a fixture-based test if you prefer.

[waketzheng]

It would be better if you could add tests.

[arturict]

Please include minimal example for new --validate option and expected user-facing messages.

[JackSpiece]

The change fixes the provided modulo and single-brace cases, but the new expression still lets either opener terminate on either closer. A {%p ... %} block can therefore stop at }}, even though only %} should close it.

Here is a full DOCX reproduction at 2c534f0:

from docx import Document
from docxtpl import DocxTemplate

doc = Document()
doc.add_paragraph("{%p set d = {'a': {}} %}")
doc.add_paragraph("{{ d }}")
doc.save("nested-dict.docx")

tpl = DocxTemplate("nested-dict.docx")
tpl.render({})

This raises TemplateSyntaxError. The equivalent plain Jinja template renders {'a': {}} correctly. At the string-transform level, patch_xml() truncates the directive to {% set d = {'a': {}} and drops its %}.

Please pair {% only with %} and {{ only with }}, then add a nested-dictionary regression case. The new focused test, all 37 repository scripts under CPython 3.12.13, and the exact flake8 command otherwise pass.