ADd missing CI environment variables.

.drone.yml

@@ -6,9 +6,13 @@ steps:
   - name: Build
     image: deukhoofd/dotnet-builder
     commands:
+      - export PATH=$PATH:$home/dotnet
+      - export DOTNET_ROOT=$PATH:$home/dotnet
       - dotnet build -c Release
   - name: Tests
     image: deukhoofd/dotnet-builder
     commands:
+      - export PATH=$PATH:$home/dotnet
+      - export DOTNET_ROOT=$PATH:$home/dotnet
       - export LD_LIBRARY_PATH=.
       - dotnet test -v n