Install GNU sed (#385)

cmer · web-flow · commit ce0f4d9a5feb · 2023-08-20T05:50:22.000+02:00
To be compatible with check_mrpe and other scripts expecting GNU sed.
diff --git a/Dockerfile b/Dockerfile
@@ -66,6 +66,7 @@ RUN apk --update --no-cache add \
     py3-pip \
     rrdtool \
     runit \
+    sed \
     shadow \
     syslog-ng=3.38.1-r0 \
     ttf-dejavu \
