misc: Add 'stdlib' tag to MAINTAINERS.yaml

This tag is for the "gem5 standard library" which can be found in
`src/python/gem5`.

Change-Id: Idf276635cd3f1d729cfbb4b7195b20fbdddd6584
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/51791
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed