feat: Upgrade default versions of apisix and apisix-dashboard (#130)

Signed-off-by: imjoey <majunjie@apache.org>
diff --git a/README.md b/README.md
index f62f0d7..ee645b9 100644
--- a/README.md
+++ b/README.md
@@ -52,7 +52,7 @@
 
 * All in one Docker container for Apache apisix-dashboard
 
-**The latest version of `apisix-dashboard` is 2.3 and should be used with APISIX 2.2.**
+**The latest version of `apisix-dashboard` is 2.4 and should be used with APISIX 2.3.**
 
 ```shell
 $ docker build --build-arg APISIX_VERSION=2.2 --build-arg APISIX_DASHBOARD_VERSION=v2.3 -t apache/apisix-dashboard:whole -f ./all-in-one/apisix-dashboard/Dockerfile .
diff --git a/alpine/Dockerfile b/alpine/Dockerfile
index a462d32..f981722 100644
--- a/alpine/Dockerfile
+++ b/alpine/Dockerfile
@@ -2,7 +2,7 @@
 
 FROM openresty/openresty:alpine-fat AS production-stage
 
-ARG APISIX_VERSION=2.2
+ARG APISIX_VERSION=2.3
 LABEL apisix_version="${APISIX_VERSION}"
 
 ARG ENABLE_PROXY
diff --git a/centos/Dockerfile b/centos/Dockerfile
index 8af56ef..bfc7562 100644
--- a/centos/Dockerfile
+++ b/centos/Dockerfile
@@ -1,6 +1,6 @@
 FROM centos:7
 
-ARG APISIX_VERSION=2.2
+ARG APISIX_VERSION=2.3
 LABEL apisix_version="${APISIX_VERSION}"
 
 RUN yum -y install yum-utils\
diff --git a/example/docker-compose.yml b/example/docker-compose.yml
index 4bd338e..62d4ed9 100644
--- a/example/docker-compose.yml
+++ b/example/docker-compose.yml
@@ -2,7 +2,7 @@
 
 services:
   apisix:
-    image: apache/apisix:2.2-alpine
+    image: apache/apisix:2.3-alpine
     restart: always
     volumes:
       - ./apisix_log:/usr/local/apisix/logs