build,charts: Bump Dex image to v2.31.2

This bumps the base image from alpine:3.15.1 to 3.16.0, which gets rid
of the latest zlib CVE
(https://nvd.nist.gov/vuln/detail/CVE-2018-25032).

See dexidp/dex@v2.31.1...v2.31.2

CHANGELOG.md

@@ -106,7 +106,7 @@
 
 - Bump Dex chart version to [0.8.2](https://artifacthub.io/packages/helm/dex/dex/0.8.2),
   Dex image has been bumped accordingly to
-  [v2.31.1](https://github.com/dexidp/dex/releases/tag/v2.31.1)
+  [v2.31.2](https://github.com/dexidp/dex/releases/tag/v2.31.2)
   (PR[#3765](https://github.com/scality/metalk8s/pull/3765))
 
 ## Release 2.11.8 (in development)

buildchain/buildchain/versions.py

@@ -113,8 +113,8 @@ def _version_prefix(version: str, prefix: str = "v") -> str:
     ),
     Image(
         name="dex",
-        version="v2.31.1",
-        digest="sha256:6d75c7b5214699941b0dd2fd3d39a4b1288868001ed324e5bb1b90978f411bfa",
+        version="v2.31.2",
+        digest="sha256:a4422334fc2fa528f0b9ca59fe1dff1f41ec66e5086facc85b32fc8d3da72a79",
     ),
     Image(
         name="etcd",

charts/dex.yaml

@@ -1,5 +1,8 @@
 image:
   repository: '__image__(dex)'
+  # NOTE: we explicitly select a tag because the latest chart doesn't include
+  # this version yet, which we still want for some security fixes
+  tag: "v2.31.2"
 
 nodeSelector:
   node-role.kubernetes.io/infra: ''

salt/metalk8s/addons/dex/deployed/chart.sls

@@ -192,7 +192,7 @@ spec:
         env:
         - name: KUBERNETES_POD_NAMESPACE
           value: metalk8s-auth
-        image: {% endraw -%}{{ build_image_name("dex", False) }}{%- raw %}:v2.31.1
+        image: {% endraw -%}{{ build_image_name("dex", False) }}{%- raw %}:v2.31.2
         imagePullPolicy: IfNotPresent
         livenessProbe:
           httpGet: