Advance the MEOS pin to e9883a1e51

[estebanzimanyi]

Advances the pinned MobilityDB commit, which carries the MEOS raster sampling
entry points (raster_value_gdal and its at/minus/ever/always siblings) and,
with them, four upstream changes the fixtures follow.

minusStbox is the complement of the corresponding at restriction
(080e218bba). Removing a box covering [2000-01-01, 2000-01-02] from a
three-instant trajectory leaves the fragment after 2000-01-02.

An h3index text literal is hexadecimal, as in h3-pg and in MobilityDB's own
288_th3index_compops test, and a numeric cell reaches the type through a
bigint cast. The fixtures use those two canonical forms. One point for the MEOS
side: a decimal string of more than sixteen digits is also valid hexadecimal, so
stringToH3 overflows and saturates to ffffffffffffffff with E_SUCCESS —
every such literal is the same invalid cell, and unrelated cells compare equal.
Direct libh3 output:

612544986753269759   err=0 cell=ffffffffffffffff valid=0
590464338553208831   err=0 cell=ffffffffffffffff valid=0
8928308280fffff      err=0 cell=08928308280fffff valid=1

The pointcloud literals carry their reserved tail (63f974c5f4,
c3a16200c0). pgpointcloud sizes a serialized point as
sizeof(SERIALIZED_POINT) - 1 + schema point size and a serialized patch from
the buffer-aligned header, both reserving bytes past the written content — three
for a point (12 - 1 + 24 = 35 bytes total), fifteen for a patch
(64 - 1 - 48 = 15). MEOS emits that tail as zeros instead of uninitialized heap.
The fixtures' hand-written literals now include the tail, so the rule stays out
of the last coordinate and every coordinate round-trips.

Full suite green on this commit: 1798 assertions in 77 test cases.