Tests: Use bundle exec rspec --backtrace

Author: amotl

.github/workflows/tests.yml

@@ -55,4 +55,4 @@ jobs:
           bundle install
 
       - name: Run tests
-        run: bundle exec rspec
+        run: bundle exec rspec --backtrace

DEVELOP.md

@@ -10,7 +10,7 @@ docker run --rm -it --publish=44200:4200 crate:5.1.1 \
 Install project and invoke test suite.
 ```shell
 bundle install
-bundle exec rspec
+bundle exec rspec --backtrace
 ```