chore(deps): update cimg/node docker tag to v21.6.0

Author: renovate[bot]

.circleci/config.yml

@@ -15,7 +15,7 @@ jobs:
 
   Lint:
     docker:
-      - image: cimg/node:21.5.0
+      - image: cimg/node:21.6.0
     steps:
       - checkout
       - run: npm version
@@ -24,15 +24,15 @@ jobs:
 
   Formatting:
     docker:
-      - image: cimg/node:21.5.0
+      - image: cimg/node:21.6.0
     steps:
       - checkout
       - run: npm ci
       - run: npm run check:format
 
   Tests:
     docker:
-      - image: cimg/node:21.5.0
+      - image: cimg/node:21.6.0
     steps:
       - checkout
       - run: npm run ci:precheck
@@ -50,7 +50,7 @@ jobs:
 
   BuildTarball:
     docker:
-      - image: cimg/node:21.5.0
+      - image: cimg/node:21.6.0
     steps:
       - checkout
       - run: npm run ci:precheck
@@ -67,7 +67,7 @@ jobs:
       framework:
         type: string
     docker:
-      - image: cimg/node:21.5.0
+      - image: cimg/node:21.6.0
     steps:
       - checkout
       - attach_workspace: