fmt: Update for Conan V2

[jwillikers]

Specify library name and version: fmt/*

closes #12162
fixes conan-io/conan#11870

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• 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 fmt/all recipe:

• [fmt] Set builddirs as empty #12162

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

[uilianries]

LGTM

[conan-center-bot]

All green in build 8 (70e01f84b10ce50d19dabdaacc6a4d39f1d4c1e9):

• fmt/5.3.0@:
  All packages built successfully! (All logs)

• fmt/6.2.1@:
  All packages built successfully! (All logs)

• fmt/7.1.3@:
  All packages built successfully! (All logs)

• fmt/8.0.1@:
  All packages built successfully! (All logs)

• fmt/8.1.1@:
  All packages built successfully! (All logs)

• fmt/9.0.0@:
  All packages built successfully! (All logs)