fix: src/Aguacongas.TheIdServer.BlazorApp/Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN11-LIBXML2-2806812
- https://snyk.io/vuln/SNYK-DEBIAN11-OPENLDAP-2808413
- https://snyk.io/vuln/SNYK-DEBIAN11-OPENSSL-2807596
- https://snyk.io/vuln/SNYK-DEBIAN11-TIFF-2823289
- https://snyk.io/vuln/SNYK-DEBIAN11-TIFF-2823291

Author: snyk-bot

src/Aguacongas.TheIdServer.BlazorApp/Dockerfile

@@ -39,7 +39,7 @@ RUN dotnet build "Aguacongas.TheIdServer.BlazorApp.csproj" -c Release -o /app/bu
 FROM build AS publish
 RUN dotnet publish "Aguacongas.TheIdServer.BlazorApp.csproj" -c Release -o /app/publish
 
-FROM nginx:1.21 AS final
+FROM nginx:stable AS final
 WORKDIR /usr/share/nginx/html
 COPY --from=publish /app/publish/wwwroot .
 COPY --from=build /src/src/Aguacongas.TheIdServer.BlazorApp/nginx.conf /etc/nginx/nginx.conf