ci(devcontainer): bump ghcr.io/devcontainers/features/dotnet

Bumps ghcr.io/devcontainers/features/dotnet from 2.1.1 to 2.1.2.

---
updated-dependencies:
- dependency-name: ghcr.io/devcontainers/features/dotnet
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

.devcontainer/devcontainer.json

@@ -9,7 +9,7 @@
   "postCreateCommand": "dotnet restore",
   "remoteUser": "vscode",
   "features": {
-    "ghcr.io/devcontainers/features/dotnet:2.1.1": {
+    "ghcr.io/devcontainers/features/dotnet:2.1.2": {
       "version": "6.0"
     },
     "ghcr.io/rocker-org/devcontainer-features/apt-packages:1": {