Rolling gotestsum back to previous version

Author: Maed223

.github/actions/test-go-tfe/action.yml

@@ -61,7 +61,7 @@ runs:
 
     - name: Install gotestsum
       shell: bash
-      run: go install gotest.tools/gotestsum@latest
+      run: go install gotest.tools/gotestsum@5768fec807c3a620b209c79845e80fb4befa5857 # v1.12.2
 
     - name: Download artifact
       id: download-artifact