Update listed maintainer for repo package files

In our self-hosted apt repo, the listed maintainer is out of date, per Sam Kleinman.

Current listed maintainer:

Maintainer: Ernie Hershey <ernie.hershey@mongodb.com>

This line can be found in all packages and packages.gz files on the apt repo for both supported platforms (Ubuntu and Debian), for all supported archs, and both MDB editions (Community and Enterprise). Here are some examples:

- https://repo.mongodb.org/apt/ubuntu/dists/xenial/mongodb-org/4.2/multiverse/binary-amd64/Packages

- https://repo.mongodb.org/apt/ubuntu/dists/bionic/mongodb-org/4.2/multiverse/binary-amd64/Packages

- https://repo.mongodb.org/apt/ubuntu/dists/xenial/mongodb-org/4.2/multiverse/binary-i386/Packages.gz

- https://repo.mongodb.org/apt/debian/dists/buster/mongodb-org/4.2/main/binary-amd64/Packages

- https://repo.mongodb.org/apt/debian/dists/stretch/mongodb-org/4.2/main/binary-amd64/Packages

- https://repo.mongodb.com/apt/debian/dists/stretch/mongodb-enterprise/4.2/main/binary-amd64/Packages

- https://repo.mongodb.com/apt/ubuntu/dists/bionic/mongodb-enterprise/4.2/multiverse/binary-amd64/Packages