* Update information in file README and file CMakeLists.txt to use cmake
  3.26 and C++14.
* Add information on how to install cmake.
* Use different GoggleTest URL for newest Git tag v1.13.0.

Fix instructions in file README

Closes #2

See merge request hifis/software/education/gitlab-ci/exercise-project!10

* Built executable is located in folder ./build/bin/ now.

Put executable into bin directory during build

See merge request hifis/software/education/gitlab-ci/exercise-project!4

* The built executable should be put into the bin folder.

Fix linting violations and errors in cmake project

Closes #1

See merge request hifis/software/education/gitlab-ci/exercise-project!2

* Fixed style guide violations detected by cpplint.
* Fixed errors in the cmake project when building the project.