chore(deps): update haproxytech/haproxy-alpine docker tag to v3

Author: renovate[bot]

Dockerfile

@@ -1,5 +1,5 @@
 # syntax=docker/dockerfile:1.6
-FROM haproxytech/haproxy-alpine:2.9
+FROM haproxytech/haproxy-alpine:3.1
 RUN apk update --no-cache && apk upgrade --no-cache openssl && apk add --no-cache gettext
 RUN mkdir -p /etc/codecov/ssl/certs && chown haproxy:haproxy /etc/codecov/ssl/certs && chown haproxy:haproxy /etc/haproxy
 COPY --chown=haproxy:haproxy --chmod=644 config/0-haproxy.conf /etc/haproxy/0-haproxy.conf.template