adios2: use openssl@4

[GunniBusch]

• Have you followed the Contributing guidelines?
• Have you checked that there aren't other open Pull Requests for the same change?
• Have you built your formula locally with brew install --build-from-source <formula> where formula is the name of the formula you're updating?
• Have you run brew audit --strict <formula> (after doing brew install <formula>) where formula is the name of the formula you're updating?

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This migrates adios2 from openssl@3 to openssl@4 and bumps revision.

AI-assisted contribution by Codex (GPT-5). Validation (source build and brew test) performed by AI.

Built and tested locally on macOS (arm64).

#278366