Update membership of Contributor Membership Workgroup

[dempseyatgithub]

Add new workgroup members, James Dempsey and Joseph Heck.

[shahmishal]

@swift-ci test

[dempseyatgithub]

Thanks! Would you mind removing Max, who recently resigned?

@xedin Yes, I compared against the workgroup membership on the Swift forums and assumed it was up to date.

I will add an emeritus section similar to other workgroups.

[dempseyatgithub]

Thanks! Would you mind removing Max, who recently resigned?

@xedin Yes, I compared against the workgroup membership on the Swift forums and assumed it was up to date.

I will add an emeritus section similar to other workgroups.

Max had already removed himself from the membership list in a previous PR. I've submitted https://github.com/swiftlang/swift-org-website/pull/800 to add Max in an emeritus member section along the lines of other workgroup pages.