Correct ARCH var in Ubuntu Dockerfiles

deployment/Dockerfile.ubuntu.arm64

@@ -7,7 +7,7 @@ ARG SDK_VERSION=3.1
 ENV SOURCE_DIR=/jellyfin
 ENV ARTIFACT_DIR=/dist
 ENV DEB_BUILD_OPTIONS=noddebs
-ENV ARCH=arm64
+ENV ARCH=amd64
 ENV IS_DOCKER=YES
 
 # Prepare Debian build environment

deployment/Dockerfile.ubuntu.armhf

@@ -7,7 +7,7 @@ ARG SDK_VERSION=3.1
 ENV SOURCE_DIR=/jellyfin
 ENV ARTIFACT_DIR=/dist
 ENV DEB_BUILD_OPTIONS=noddebs
-ENV ARCH=armhf
+ENV ARCH=amd64
 ENV IS_DOCKER=YES
 
 # Prepare Debian build environment