CI: remove containerd v1.6 as it reached EOL

Signed-off-by: Akihiro Suda <[email protected]>

Author: AkihiroSuda

.github/workflows/workflow-test.yml

@@ -48,7 +48,7 @@ jobs:
           - runner: ubuntu-24.04-arm
           # Additionally build for old containerd on amd
           - runner: ubuntu-24.04
-            containerd-version: v1.6.38
+            containerd-version: v1.7.28
     with:
       runner: ${{ matrix.runner }}
       containerd-version: ${{ matrix.containerd-version }}
@@ -75,7 +75,7 @@ jobs:
           # old containerd + old ubuntu + old rootlesskit
           - runner: ubuntu-22.04
             target: rootless
-            containerd-version: v1.6.38
+            containerd-version: v1.7.28
             rootlesskit-version: v1.1.1
           # gomodjail
           - runner: ubuntu-24.04
@@ -91,7 +91,7 @@ jobs:
           # old containerd + old ubuntu
           - runner: ubuntu-22.04
             target: rootful
-            containerd-version: v1.6.38
+            containerd-version: v1.7.28
           # ipv6
           - runner: ubuntu-24.04
             target: rootful

docs/dev/auditing_dockerfile.md

@@ -103,9 +103,7 @@ ci_run(){
   local no_cache="${1:-}"
   export UBUNTU_VERSION=24.04
 
-  CONTAINERD_VERSION=v1.6.36 run "$no_cache" arm64 Dockerfile.origin build-dependencies
-  UBUNTU_VERSION=20.04 CONTAINERD_VERSION=v1.6.36 run "" arm64 Dockerfile.origin test-integration
-
+  # The actual version may differ
   CONTAINERD_VERSION=v1.7.25 run "$no_cache"  arm64 Dockerfile.origin build-dependencies
   UBUNTU_VERSION=22.04 CONTAINERD_VERSION=v1.7.25 run "" arm64 Dockerfile.origin test-integration
 

hack/generate-release-note.sh

@@ -25,7 +25,8 @@ cat <<-EOX
 (To be documented)
 
 ## Compatible containerd versions
-This release of nerdctl is expected to be used with containerd v1.6, v1.7, v2.0, or v2.1.
+This release of nerdctl is expected to be used with containerd v1.7, v2.0, or v2.1.
+Some features may not work with other releases of containerd.
 
 ## About the binaries
 - Minimal (\`${minimal_amd64tgz_basename}\`): nerdctl only