FIX: Added iwyu in Dockerfile

.docker/Dockerfile

@@ -2,7 +2,8 @@ FROM debian:bookworm
 
 RUN apt-get update
 RUN apt-get install -y cmake
-RUN apt-get install -y lcov
+# iwyu is not a strict dependency here, but in the cppinttests.
+RUN apt-get install -y lcov iwyu
 RUN apt-get install -y doxygen graphviz
 RUN apt-get install -y clang-format-16 clang-tidy-16
 RUN apt-get install -y python3-pip python3-venv

doc/DEPENDENCIES.md

@@ -40,7 +40,7 @@ clang-tidy-16
 
 ```
 >=gcc-10.2.0
->=lcov-1.15
+>=lcov-1.16
 ```
 
 ## Formatting ##