chore: update golang image

Signed-off-by: Mark Sagi-Kazar <mark.sagikazar@gmail.com>

Dockerfile

-ARG BASEIMAGE=alpine:3.15.0
+ARG BASEIMAGE=alpine:3.15.1
 
-FROM golang:1.17.6-alpine3.14 AS builder
+FROM golang:1.17.8-alpine3.15 AS builder
 
 WORKDIR /usr/local/src/dex
 
@@ -22,13 +22,13 @@ COPY . .
 
 RUN make release-binary
 
-FROM alpine:3.15.0 AS stager
+FROM alpine:3.15.1 AS stager
 
 RUN mkdir -p /var/dex
 RUN mkdir -p /etc/dex
 COPY config.docker.yaml /etc/dex/
 
-FROM alpine:3.15.0 AS gomplate
+FROM alpine:3.15.1 AS gomplate
 
 ARG TARGETOS
 ARG TARGETARCH