fix: switch Dockerfile base image to alpine and install dependencies using apk

Dockerfile

@@ -1,9 +1,9 @@
-FROM node:20-slim
+FROM alpine
 
-RUN apt-get update && \
-    apt-get install -y --no-install-recommends git && \
-    rm -rf /var/lib/apt/lists/* && \
-    git --version
+RUN apk add --no-cache nodejs npm git \
+    && node --version \
+    && npm --version \
+    && git --version
 
 WORKDIR /action