ci: update alpine to 3.21

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

Author: crazy-max

.github/workflows/build.yml

@@ -35,10 +35,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          -
-            image: alpine:3.16
-            typ: alpine
-            allow-failure: false
           -
             image: alpine:3.17
             typ: alpine
@@ -55,6 +51,10 @@ jobs:
             image: alpine:3.20
             typ: alpine
             allow-failure: false
+          -
+            image: alpine:3.21
+            typ: alpine
+            allow-failure: false
           -
             image: alpine:edge
             typ: alpine