build: bump docker-gen from 0.8.4 to 0.9.0

Dockerfile

@@ -1,9 +1,9 @@
 # setup build arguments for version of dependencies to use
-ARG DOCKER_GEN_VERSION=0.8.4
+ARG DOCKER_GEN_VERSION=0.9.0
 ARG FOREGO_VERSION=v0.17.0
 
 # Use a specific version of golang to build both binaries
-FROM golang:1.17.8 as gobuilder
+FROM golang:1.18.0 as gobuilder
 
 # Build docker-gen from scratch
 FROM gobuilder as dockergen

Dockerfile.alpine

@@ -1,9 +1,9 @@
 # setup build arguments for version of dependencies to use
-ARG DOCKER_GEN_VERSION=0.8.4
+ARG DOCKER_GEN_VERSION=0.9.0
 ARG FOREGO_VERSION=v0.17.0
 
 # Use a specific version of golang to build both binaries
-FROM golang:1.17.8-alpine as gobuilder
+FROM golang:1.18.0-alpine as gobuilder
 RUN apk add --no-cache git musl-dev
 
 # Build docker-gen from scratch