fix: install mailcap in running-image not building-image

Author: MonstraG

Dockerfile

@@ -27,9 +27,6 @@ RUN go mod download
 # install git so that go will be able to write down current version when building
 RUN apk add --no-cache git
 
-# install mailcap to add mime type support, https://stackoverflow.com/a/38033047
-RUN apk add --no-cache mailcap
-
 # run go build, name the executable "go-api" and also disable CGO because people keep telling me that
 RUN CGO_ENABLED=0 go build -o go-api
 
@@ -40,6 +37,9 @@ FROM alpine:${ALPINE_VERSION} AS running-image
 # ensure sqlite is available on running-image
 RUN apk add --no-cache sqlite
 
+# install mailcap to add mime type support, https://stackoverflow.com/a/38033047
+RUN apk add --no-cache mailcap
+
 # copy everything from our folder (so, repo + built executable) from our building-image into the same folder but into the second image
 # also exclude all the source files, so the final build is even smaller (although it saves like 20kb)
 # finally, exclude .git folder, we needed it in building-image to bake in version information, but not anymore