Maint: rename BUILD_DATE to CREATED

Dockerfile

@@ -43,24 +43,24 @@ FROM --platform=${BUILDPLATFORM} base AS build
 ARG TARGETPLATFORM
 ARG ALLTARGETPLATFORMS=${TARGETPLATFORM}
 ARG VERSION=unknown
-ARG BUILD_DATE="an unknown date"
+ARG CREATED="an unknown date"
 ARG COMMIT=unknown
 RUN xcputranslate sleep -targetplatform ${TARGETPLATFORM} -buildtime=10s -order=${ALLTARGETPLATFORMS}
 RUN GOARCH="$(xcputranslate translate -field arch -targetplatform ${TARGETPLATFORM})" \
     GOARM="$(xcputranslate translate -field arm -targetplatform ${TARGETPLATFORM})" \
     go build -trimpath -ldflags="-s -w \
     -X 'main.version=$VERSION' \
-    -X 'main.buildDate=$BUILD_DATE' \
+    -X 'main.buildDate=$CREATED' \
     -X 'main.commit=$COMMIT' \
     " -o entrypoint cmd/gluetun/main.go
 
 FROM alpine:${ALPINE_VERSION}
 ARG VERSION=unknown
-ARG BUILD_DATE="an unknown date"
+ARG CREATED="an unknown date"
 ARG COMMIT=unknown
 LABEL \
     org.opencontainers.image.authors="quentin.mcgaw@gmail.com" \
-    org.opencontainers.image.created=$BUILD_DATE \
+    org.opencontainers.image.created=$CREATED \
     org.opencontainers.image.version=$VERSION \
     org.opencontainers.image.revision=$COMMIT \
     org.opencontainers.image.url="https://github.com/qdm12/gluetun" \