[gtest] Requires Conan 1.51.1 or higher

[uilianries]

The self.info.settings.get_safe requires Conan 1.51.1: https://github.com/qpdf/qpdf#crypto-providers

Trying to build GTest with 1.50.0, you will get:

ERROR: gtest/1.12.1: Error in validate() method, line 80
	if self.info.settings.get_safe("compiler.cppstd"):
	TypeError: 'NoneType' object is not callable

---

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the conan-center hook activated.

[ghost]

I detected other pull requests that are modifying gtest/all recipe:

• gtest: set the correct required_conan_version + few minor fixes #13121

This message is automatically generated by https://github.com/ericLemanissier/conan-center-conflicting-prs so don't hesitate to report issues/improvements there.

[conan-center-bot]

All green in build 1 (b43d805fd4c5061c60f4e678a58575466d073488):

• gtest/1.12.1@:
  All packages built successfully! (All logs)

[uilianries]

duplicated with #13121