Update pydantic-ai requirement from <2,>=1.56.0 to >=1.87.0,<2

Updates the requirements on [pydantic-ai](https://github.com/pydantic/pydantic-ai) to permit the latest version.
- [Release notes](https://github.com/pydantic/pydantic-ai/releases)
- [Changelog](https://github.com/pydantic/pydantic-ai/blob/main/docs/changelog.md)
- [Commits](pydantic/pydantic-ai@v1.56.0...v1.87.0)

---
updated-dependencies:
- dependency-name: pydantic-ai
  dependency-version: 1.86.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements/base.txt

@@ -48,7 +48,7 @@ pdf2image>=1.16.0
 tiktoken==0.12.0  # https://github.com/openai/tiktoken
 openai>=2.11.0,<3  # https://github.com/openai/openai-python (pydantic-ai 1.x requires >=2.11.0)
 pytesseract
-pydantic-ai>=1.56.0,<2
+pydantic-ai>=1.87.0,<2
 spacy
 pdfplumber>=0.10.0  # https://github.com/jsvine/pdfplumber - PDF token extraction
 shapely>=2.0.0  # https://github.com/shapely/shapely - spatial operations for bbox intersection