add gcovr

Author: niteshpurohit

Dockerfile

@@ -21,4 +21,10 @@ RUN wget -q https://github.com/catchorg/Catch2/archive/refs/tags/v3.7.1.zip && \
   unzip v3.7.1.zip && \
   cd Catch2-3.7.1 && \
   cmake -Bbuild -H. -DBUILD_TESTING=OFF && \
-  cmake --build build/ --target install
+  cmake --build build/ --target install
+
+# Install python3
+RUN apt-get install -y python3 python3-pip python3-full
+
+# Install gcovr
+RUN pip3 install gcovr --break-system-packages