Update pin for mpich

[regro-cf-autotick-bot]

This PR has been triggered in an effort to update the pin for mpich. The current pinned version is 4, the latest available version is 5 and the max pin pattern is x. This migration will impact 139 feedstocks.

Checklist:

• The new version is a stable supported pin.
• I checked that the ABI changed from 4 to 5.

**Please note that if you close this PR we presume that the new pin has been rejected.

@conda-forge-admin please ping mpich

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[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-webservice.

I was asked to ping @conda-forge/mpich and so here I am doing that.

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.

I do have some suggestions for making it better though...

For recipe/meta.yaml:

• ℹ️ The recipe is not parsable by parser conda-recipe-manager. The recipe can only be automatically migrated to the new v1 format if it is parseable by conda-recipe-manager.

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