Add CI dependency coveralls to our Pipfile

The dependency `coveralls` was installed directly in GitHub Actions, as
it's not required for local dev environments. However, it's a small
package and there's value in keeping all our dependency specifications
in one place. That's why I've moved it to the [dev] section of our
Pipfile.

Signed-off-by: Sebastiaan Zeeff <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/Pipfile b/Pipfile
index b8a542653..0730b9150 100644
--- a/Pipfile
+++ b/Pipfile
@@ -39,6 +39,7 @@ flake8-tidy-imports = "~=4.0"
 flake8-todo = "~=0.7"
 pep8-naming = "~=0.9"
 pre-commit = "~=2.1"
+coveralls = "~=2.1"
 
 [requires]
 python_version = "3.8"