Add ext/ to Dockerfile and .deb build helper

Dockerfile

 FROM perl:5.30-slim
 
 COPY bin/ /app/bin/
+COPY ext/ /app/ext/
 COPY lib/ /app/lib/
 COPY Build.PL cpanfile* /app/
 

scripts/makedeb-docker-helper

@@ -20,7 +20,7 @@ apt-cache dumpavail | dpkg --merge-avail
 
 mkdir -p /src/app
 cp -a /orig/Build.PL /orig/Changelog /orig/README.md /src/app
-cp -a /orig/bin /orig/lib /src/app
+cp -a /orig/bin /orig/ext /orig/lib /src/app
 cd /src/app
 
 sed -i 's/sign *=> *1/sign => 0/' Build.PL