Revert "postgresql: update to version 16.3"

Revert "postgresql: update to version 16.3"

This reverts commit 6a46887e60d969cf718de3a212aa1847277ed4b3
from PR https://github.com/openwrt/packages/pull/24327

Postgresql version upgrade fails in buildbot for all targets
with error like:

[236/1612] Generating src/fe_utils/psqlscan with a custom command
FAILED: src/fe_utils/psqlscan.c
/builder/shared-workdir/build/sdk/staging_dir/host/bin/python3 ../src/tools/pgflex --builddir . --srcdir .. --privatedir src/fe_utils/psqlscan.c.p --flex /builder/shared-workdir/build/sdk/staging_dir/host/bin/flex --perl /builder/shared-workdir/build/sdk/staging_dir/host/bin/perl -i ../src/fe_utils/psqlscan.l -o src/fe_utils/psqlscan.c --no-backup --fix-warnings -- -Cfe -p -p
flex: fatal internal error, exec of /builder/shared-workdir/build/staging_dir/host/bin/m4 failed
[237/1612] Compiling C object src/interfaces/libpq/libpq.so.5.16.p/pqexpbuffer.c.o
ninja: build stopped: subcommand failed.
make[3]: *** [Makefile:264: /builder/shared-workdir/build/sdk/build_dir/target-aarch64_cortex-a53_musl/postgresql-16.3/.built] Error 1

Several dozen packages depend upon postgresql, so the fallout is
rather large. Let's revert the upgrade until a fix is found.

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>