interim patch install from pyroute2 fork

This is an important patch of lingering scrape time build up issue over time.

Also the frequency of json DecodeError issues is addressed with this.

Dockerfile

@@ -13,6 +13,14 @@ RUN set -ex \
         && cd /prometheus-ss-exporter \
         && python3 setup.py install
 
+# interim -- install ss2 from forked pyroute2
+RUN /bin/bash -c "git clone https://github.com/cherusk/pyroute2.git \
+                  && pushd pyroute2 \
+                  && git checkout -B  origin/ss2_patch_class_level_data \
+                  && python3 setup.py install \
+                  && popd \
+                  && rmdir --ignore-fail-on-non-empty pyroute2"
+
 EXPOSE 8090
 
 HEALTHCHECK --interval=1s --timeout=2s --retries=1 \