Update build-wasm.sh

Adjust for nuget_path location in prebuild

build/gitpod/build-wasm.sh

@@ -2,6 +2,8 @@
 
 pushd src/SamplesApp/SamplesApp.Wasm
 
+export NUGET_PACKAGES=/workspace/.nuget
+
 GITPOD_HOSTNAME=`echo $GITPOD_WORKSPACE_URL | sed -s 's/https:\/\///g'`
 
 msbuild /r /bl SamplesApp.Wasm.csproj /p:UnoSourceGeneratorUseGenerationHost=true /p:UnoSourceGeneratorUseGenerationController=false /p:UnoRemoteControlPort=443 "/p:UnoRemoteControlHost=https://53487-$GITPOD_HOSTNAME"