build: run integration tests on main branch after push

[olavloite]

Run the integration tests on the main branch after push to ensure that
the change does not break anything, and to create a baseline for code
coverage reports.

[codecov]

Codecov Report

Merging #270 (ddab116) into postgresql-dialect (ce01b5c) will not change coverage.
The diff coverage is n/a.

@@                  Coverage Diff                  @@
##             postgresql-dialect     #270   +/-   ##
=====================================================
  Coverage                 80.87%   80.87%           
  Complexity                 1167     1167           
=====================================================
  Files                        95       95           
  Lines                      3943     3943           
  Branches                    488      488           
=====================================================
  Hits                       3189     3189           
  Misses                      578      578           
  Partials                    176      176           

Flag	Coverage Δ
all_tests	80.87% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ce01b5c...ddab116. Read the comment docs.