[CI] Update CPU image to v0.81

Author: masahi

Jenkinsfile

@@ -47,7 +47,7 @@ import org.jenkinsci.plugins.pipeline.modeldefinition.Utils
 // NOTE: these lines are scanned by docker/dev_common.sh. Please update the regex as needed. -->
 ci_lint = "tlcpack/ci-lint:v0.68"
 ci_gpu = "tlcpack/ci-gpu:v0.81"
-ci_cpu = "tlcpack/ci-cpu:v0.80"
+ci_cpu = "tlcpack/ci-cpu:v0.81"
 ci_wasm = "tlcpack/ci-wasm:v0.71"
 ci_i386 = "tlcpack/ci-i386:v0.74"
 ci_qemu = "tlcpack/ci-qemu:v0.10"