automation: use gp3 volume type
This is a newer volume type. It offers a better baseline of performance
by default and is ~10% cheaper. It doesn't offer burst credits. But
its performance is guaranteed, unlike gp2, which had wonky performance
behavior.
Differential Revision: https://phab.mercurial-scm.org/D12132
# Files that just need to be migrated to the formatter.
# Do not add new files here!
mercurial/cext/manifest.c
mercurial/cext/osutil.c
# Vendored code that we should never format:
syntax: glob
contrib/python-zstandard/**.c
contrib/python-zstandard/**.h
hgext/fsmonitor/pywatchman/**.c
mercurial/thirdparty/**.c
mercurial/thirdparty/**.h
mercurial/pythoncapi_compat.h