Fix mangled Dockerfiles

Dockerfile

@@ -2,7 +2,7 @@ ARG DOTNET_VERSION=3.1
 ARG FFMPEG_VERSION=latest
 
 FROM node:alpine as web-builder
-10.5.1
+ARG JELLYFIN_WEB_VERSION=10.5.1
 RUN apk add curl git \
  && curl -L https://github.com/jellyfin/jellyfin-web/archive/${JELLYFIN_WEB_VERSION}.tar.gz | tar zxf - \
  && cd jellyfin-web-* \

Dockerfile.arm

@@ -6,7 +6,7 @@ ARG DOTNET_VERSION=3.1
 
 
 FROM node:alpine as web-builder
-10.5.1
+ARG JELLYFIN_WEB_VERSION=10.5.1
 RUN apk add curl git \
  && curl -L https://github.com/jellyfin/jellyfin-web/archive/${JELLYFIN_WEB_VERSION}.tar.gz | tar zxf - \
  && cd jellyfin-web-* \

Dockerfile.arm64

@@ -6,7 +6,7 @@ ARG DOTNET_VERSION=3.1
 
 
 FROM node:alpine as web-builder
-10.5.1
+ARG JELLYFIN_WEB_VERSION=10.5.1
 RUN apk add curl git \
  && curl -L https://github.com/jellyfin/jellyfin-web/archive/${JELLYFIN_WEB_VERSION}.tar.gz | tar zxf - \
  && cd jellyfin-web-* \