ci: Potential ci fix

Dockerfile

@@ -1,4 +1,4 @@
-FROM mcr.microsoft.com/dotnet/sdk:7.0 AS build
+FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
 WORKDIR /source
 
 COPY src/Nadeko.Medusa/*.csproj src/Nadeko.Medusa/
@@ -20,7 +20,7 @@ RUN set -xe; \
     chmod +x /app/NadekoBot
 
 # final stage/image
-FROM mcr.microsoft.com/dotnet/runtime:6.0
+FROM mcr.microsoft.com/dotnet/runtime:8.0
 WORKDIR /app
 
 RUN set -xe; \