openbsd_pkg: Fix KeyError (#3336)

If package installation has an error after the package is install (e.g.
when running tags), then there will be output on stderr and the fallback
regex will match; however, since pkg_add exited non-zero, changed is
never added as a key to the dictionary. As a result the code at the end
of main that checks if anything has changed raises a KeyError.

changelogs/fragments/3336-openbsd_pkg-fix-KeyError.yml

@@ -0,0 +1,5 @@
+---
+bugfixes:
+  - openbsd_pkg - fix crash from ``KeyError`` exception when package installs,
+    but ``pkg_add`` returns with a non-zero exit code
+    (https://github.com/ansible-collections/community.general/pull/3336).

plugins/modules/packaging/os/openbsd_pkg.py

@@ -246,6 +246,7 @@ def package_present(names, pkg_spec, module):
                     if match:
                         # It turns out we were able to install the package.
                         module.debug("package_present(): we were able to install package for name '%s'" % name)
+                        pkg_spec[name]['changed'] = True
                     else:
                         # We really did fail, fake the return code.
                         module.debug("package_present(): we really did fail for name '%s'" % name)