ci: Add missing buildx step to CI workflow #1327

Job	Run time
test	2m 16s
Build Docker Image	2m 38s
pre-commit	16s
build (linux, arm64)	1m 29s
build (linux, amd64)	1m 34s
build (darwin, arm64)	1m 36s
build (darwin, amd64)	1m 48s
build (windows, amd64)	1m 36s
integration test (kindest/node:v1.19.16)	1m 25s
integration test (kindest/node:v1.20.15)	1m 15s
integration test (kindest/node:v1.21.14)	1m 12s
integration test (kindest/node:v1.22.15)	1m 12s
integration test (kindest/node:v1.23.13)	1m 16s
integration test (kindest/node:v1.24.7)	1m 18s
integration test (kindest/node:v1.25.3)	1m 10s
integration test (kindest/node:v1.26.6)	1m 10s
integration test (kindest/node:v1.27.3)	1m 16s
integration test (kindest/node:v1.28.0)	1m 9s
Create Release	0s
Push Image	0s
Release Artifacts	0s
	25m 36s

Provide feedback