Configure nextest to run database tests serially

.config/nextest.toml

@@ -0,0 +1,14 @@
+[test-groups]
+database = { max-threads = 1 }
+
+[profile.default]
+retries = 1
+
+# sqlx has a problem with nextest, as it uses a process-local semaphore to have
+# tests use different databases. This doesn't work with nextest, as it has a
+# process-per-test model, which is why we need to make sure only one test uses
+# the database at a time.
+# See https://github.com/launchbadge/sqlx/pull/3334
+[[profile.default.overrides]]
+filter = 'package(mas-handlers) or package(mas-storage-pg)'
+test-group = 'database'