Update GitHub Actions workflows. (#799)

This PR was triggered by @t0yv0 generated by the
update-workflows-ecosystem-providers workflow in the pulumi/ci-mgmt
repo, from commit
[4eeb9c0311bcea38a166c43eb897cf2a2f88ea4c](4eeb9c0311).

Co-authored-by: Pulumi Bot <bot@pulumi.com>

.config/mise.test.toml

@@ -1,3 +1,4 @@
 # WARNING: This file is autogenerated - changes will be overwritten when regenerated by https://github.com/pulumi/ci-mgmt
 
-# Overrides for test workflows -- currently empty.
+[tools]
+"aqua:gotestyourself/gotestsum" = "1.12.0"

.github/workflows/copilot-setup-steps.yml

@@ -1,26 +0,0 @@
-name: "Copilot Setup Steps"
-
-# This workflow configures the environment for GitHub Copilot Agent with gh-aw MCP server
-on:
-  workflow_dispatch:
-  push:
-    paths:
-      - .github/workflows/copilot-setup-steps.yml
-
-jobs:
-  # The job MUST be called 'copilot-setup-steps' to be recognized by GitHub Copilot Agent
-  copilot-setup-steps:
-    runs-on: ubuntu-latest
-
-    # Set minimal permissions for setup steps
-    # Copilot Agent receives its own token with appropriate permissions
-    permissions:
-      contents: read
-
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@v6
-      - name: Install gh-aw extension
-        uses: github/gh-aw/actions/setup-cli@v0.56.2
-        with:
-          version: v0.56.2