add Alex to GH mgmt stewards

[galargh]

Summary

Why do you need this?

What else do we need to know?

DRI: myself

Reviewer's Checklist

• It is clear where the request is coming from (if unsure, ask)
• All the automated checks passed
• The YAML changes reflect the summary of the request
• The Terraform plan posted as a comment reflects the summary of the request

[github-actions]

Before merge, verify that all the following plans are correct. They will be applied as-is after the merge.

Terraform plans

libp2p

Terraform used the selected providers to generate the following execution
plan. Resource actions are indicated with the following symbols:
  + create
  ~ update in-place

Terraform will perform the following actions:

  # github_repository_file.this["js-http-v1-content-routing/.github/workflows/stale.yml"] will be updated in-place
  ~ resource "github_repository_file" "this" {
      + commit_author       = "GitHub"
      + commit_email        = "[email protected]"
        id                  = "js-http-v1-content-routing/.github/workflows/stale.yml"
        # (9 unchanged attributes hidden)
    }

  # github_team_membership.this["github-mgmt stewards:achingbrain"] will be created
  + resource "github_team_membership" "this" {
      + etag     = (known after apply)
      + id       = (known after apply)
      + role     = "member"
      + team_id  = "6630941"
      + username = "achingbrain"
    }

Plan: 1 to add, 1 to change, 0 to destroy.

[achingbrain]

Unrelated change?

[galargh]

It's an automatic fix, because I didn't merge #169 before. It'll get rebased in a sec. I'll merge afterwards.