update go version to 1.21 in cirrus ci

Signed-off-by: lfbzhm <[email protected]>

Author: lifubang

.cirrus.yml

@@ -77,7 +77,7 @@ task:
   env:
     HOME: /root
     CIRRUS_WORKING_DIR: /home/runc
-    GO_VERSION: "1.20"
+    GO_VERSION: "1.21"
     BATS_VERSION: "v1.9.0"
     RPMS: gcc git iptables jq glibc-static libseccomp-devel make criu fuse-sshfs container-selinux
     # yamllint disable rule:key-duplicates