Upgrade base image to m80 (#1080)

Author: rosbo

Dockerfile.tmpl

@@ -1,9 +1,9 @@
 {{ if eq .Accelerator "gpu" }}
-FROM gcr.io/deeplearning-platform-release/tf2-gpu.2-6:m78
+FROM gcr.io/deeplearning-platform-release/tf2-gpu.2-6:m80
 ENV CUDA_MAJOR_VERSION=11
 ENV CUDA_MINOR_VERSION=0
 {{ else }}
-FROM gcr.io/deeplearning-platform-release/tf2-cpu.2-6:m78
+FROM gcr.io/deeplearning-platform-release/tf2-cpu.2-6:m80
 {{ end }}
 # Keep these variables in sync if base image is updated.
 ENV TENSORFLOW_VERSION=2.6.0