meson: Add missing dependencies to libpq_pipeline test

The missing dependency was, e.g., visible when doing
  ninja clean && ninja meson-test-prereq && meson test --no-rebuild --suite setup --suite libpq_pipeline

Apply this to all branches with meson support, as part of an effort to fix
incorrect test dependencies that can lead to test failures.

Discussion: https://postgr.es/m/CAGECzQSvM3iSDmjF+=Kof5an6jN8UbkP_4cKKT9w6GZavmb5yQ@mail.gmail.com
Discussion: https://postgr.es/m/bdba588f-69a9-4f3e-9b95-62d07210a32e@eisentraut.org
Backpatch: 16-, where meson support was added

src/test/modules/libpq_pipeline/meson.build

@@ -27,5 +27,6 @@ tests += {
     'tests': [
       't/001_libpq_pipeline.pl',
     ],
+    'deps': [libpq_pipeline],
   },
 }