How to renew letsecncrypt certificates with the same public key

I am using Traefik 1.7 for APIs serving mobile apps that require to use certificate pinning to the public key, and I don't find anywhere in the docs how I can configure acme to reuse the same public key when renewing the certificates, I believe that would be like the --reuse-key in certbot:

--reuse-key           When renewing, use the same private key as the existing certificate. (default: False)

My traefik.tom file:

debug = false

logLevel = "ERROR"
defaultEntryPoints = ["https","http"]

[entryPoints]
  [entryPoints.http]
  address = ":80"
    [entryPoints.http.redirect]
    entryPoint = "https"

  [entryPoints.https]
  address = ":443"
  [entryPoints.https.tls]

[retry]

[docker]
endpoint = "unix:///var/run/docker.sock"
watch = true
exposedByDefault = false

[acme]
storage = "acme.json"
entryPoint = "https"
onHostRule = true
[acme.httpChallenge]
entryPoint = "http"

My docker-compose.yml file:

version: '2.3'

services:
  traefik:
    image: traefik:1.7
    restart: always
    ports:
      - 80:80
      - 443:443
    networks:
      - traefik
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - ./traefik.toml:/traefik.toml
      - ./acme.json:/acme.json
    container_name: traefik
    labels:
      - "traefik.acme.email=${TRAEFIK_ACME_EMAIL:? Missing TRAEFIK_ACME_EMAIL env var.}"
      - "traefik.docker.domain=${TRAEFIK_DOCKER_DOMAIN:? Missing TRAEFIK_DOCKER_DOMAIN env var.}"
networks:
  traefik:
    external: true