added apk upgrade to dockerfile

Dockerfile

@@ -1,15 +1,19 @@
 FROM alpine:latest
 
-RUN echo "http://dl-cdn.alpinelinux.org/alpine/v3.10/community" >> /etc/apk/repositories
+RUN apk upgrade --no-cache
-
-# install required packages
-#RUN apk add --no-cache gcc libc-dev libffi-dev openssl openssl-dev python3-dev
-RUN apk add --no-cache apache2 apache2-utils apache2-webdav mod_dav_svn subversion
 
 # add user that will be used to install and run the application
 RUN addgroup -g 1000 deploy
 RUN adduser -D -u 1000 -G deploy deploy
 
+#
+# CUSTOM PART IS BELOW HERE
+#
+
+# install required packages
+RUN echo "http://dl-cdn.alpinelinux.org/alpine/v3.10/community" >> /etc/apk/repositories
+RUN apk add --no-cache apache2 apache2-utils apache2-webdav mod_dav_svn subversion
+
 # add svn configuration
 ADD dav_svn.conf /etc/apache2/conf.d/dav_svn.conf