suite-sparse BUG: Fix conflicting openblas dependencies

This was breaking the formula for e.g. numpy --with-openblas because of conflicting dependencies: numpy asks for homebrew/science/openblas while suite-sparse just asked for openblas, and homebrew did not realize they were the same thing. This seems to be a recurring issue that was causing a lot of problems.

edit: as this seems like the type of issue that can come up easily and be difficult to track down, I applied the same change to the metis4 dependency. This might be worth adding to the Formula style guide.