Simplify Docker build

- Remove unnecessary build command (implied in publish)
- Remove unnecessary solution arg
- Move arg to command

Dockerfile

@@ -3,11 +3,9 @@ ARG DOTNET_VERSION=2
 FROM microsoft/dotnet:${DOTNET_VERSION}-sdk as builder
 WORKDIR /repo
 COPY . .
-ARG CONFIGURATION=RELEASE
 RUN export DOTNET_CLI_TELEMETRY_OPTOUT=1 \
  && dotnet clean \
- && dotnet build --configuration ${CONFIGURATION} $(pwd)/MediaBrowser.sln \
- && dotnet publish --configuration ${CONFIGURATION} $(pwd)/MediaBrowser.sln --output /jellyfin
+ && dotnet publish --configuration release --output /jellyfin
 
 FROM microsoft/dotnet:${DOTNET_VERSION}-runtime
 COPY --from=builder /jellyfin /jellyfin