Use alpine:3.13.5, update curl

Dockerfile

-FROM alpine:3.13
+FROM alpine:3.13.5
 
 LABEL name="OpenAppStack management"
-LABEL version="4.1"
+LABEL version="4.2"
 LABEL vendor1="Greenhost"
 
 
@@ -14,9 +14,9 @@ RUN \
     cargo=~1.47.0-r2 \
     chromium=~86.0.4240.111-r0 \
     chromium-chromedriver=~86.0.4240.111-r0 \
-    curl=~7.74.0-r1 \
+    curl=~7.76.1-r0 \
     # needed for installing pycurl python module
-    curl-dev=~7.74.0-r1 \
+    curl-dev=~7.76.1-r0 \
     gcc=~10.2.1_pre1-r3 \
     git=~2.30.2-r0 \
     libffi-dev=3.3-r2 \
@@ -32,4 +32,3 @@ RUN \
   update-ca-certificates && \
   pip install --no-cache-dir -r /requirements.txt && \
   ln -s /usr/bin/python3 /usr/bin/python
-