Update mcr.microsoft.com/dotnet/sdk Docker tag to v9.0.305 (#270)

Co-authored-by: projectorigin-renovate[bot] <150237208+projectorigin-renovate[bot]@users.noreply.github.com>

Author: projectorigin-renovate[bot]

src/Stamp.Dockerfile

@@ -1,6 +1,6 @@
 ARG PROJECT=ProjectOrigin.Stamp.Server
 
-FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:9.0.304 AS build
+FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:9.0.305 AS build
 ARG PROJECT
 
 WORKDIR /src