chore(deps): update dependency prometheus-cpp to v1.2.4 (#63)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

conanfile.txt

@@ -6,7 +6,7 @@
 [requires]
   # prometheus-cpp 1.1.0 cannot be used because it supports only C++14 onward; however the compiler shipping with Centos7
   # supports at most the C++11 dialect... so till we want to support Centos7, we need to stick with prometheus-cpp 1.0.0
-  prometheus-cpp/1.0.0@
+  prometheus-cpp/1.2.4@
 
 [options]
   # by using shared=False we create a cmonitor_collector binary that is self-contained