[docker] Bump alpine from 3.21.1 to 3.21.2

Bumps alpine from 3.21.1 to 3.21.2.

---
updated-dependencies:
- dependency-name: alpine
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.21.1 AS builder
+FROM alpine:3.21.2 AS builder
 
 ARG TARGETPLATFORM
 
@@ -22,7 +22,7 @@ RUN COLOUR='\e[1;93m' && \
   pip install -r /app/requirements.txt && \
   echo -e "${COLOUR}Done.\e[0m"
 
-FROM alpine:3.21.1
+FROM alpine:3.21.2
 LABEL maintainer="Patrick Baus <patrick.baus@physik.tu-darmstadt.de>"
 LABEL description="Kraken sensor data aggregator."