Use Alpine main repo version 3.16 for adding package libexecinfo-dev

Alpine versions above 3.16 do not contain package libexecinfo-dev, which
ATS needs.

.github/containers/trafficserver-alpine/Dockerfile

@@ -23,18 +23,23 @@ RUN set -o errexit -o nounset -o xtrace; \
     dirname=trafficserver-${ATS_VERSION}; \
     tar xf ${dirname}.tar.bz2; \
     rm ${dirname}.tar.bz2; \
-    apk add --no-cache \
+    apk add --update --no-cache \
         # configure dependencies
         g++ \
         perl \
         openssl-dev \
         pcre-dev \
         make \
         # build dependencies
-        libexecinfo-dev \
         fortify-headers \
         linux-headers \
         zlib-dev; \
+    # Alpine versions above 3.16 do not contain package libexecinfo-dev,
+    # which ATS needs.
+    # https://github.com/aws/aws-lambda-nodejs-runtime-interface-client/issues/68#issuecomment-1571877109
+    apk add --update --no-cache \
+        --repository=https://dl-cdn.alpinelinux.org/alpine/v3.16/main/ \
+        libexecinfo-dev \
     cd $dirname; \
     ./configure \
         --disable-tests \
@@ -52,7 +57,7 @@ RUN set -o errexit -o nounset -o xtrace; \
     cd ..; \
     rm -r $dirname
 
-FROM alpine:latest
+FROM alpine:3.16
 COPY --from=build-trafficserver /tmp/built/ /
 RUN apk add --no-cache \
         # runtime dependencies