allow to free result after stream closed

[DavidBadura]

It looks like PDOStatement::closeCursor() doesn't really work in postgres, but is released via the garbage collector.

Our stream deletes all references after close so that the garbage collector can work.

fix pipeline for #526

[github-actions]

Hello 👋

here is the most recent benchmark result:

SnapshotsBench
==============

+----------------------------------------+--------------------+--------------------+-----------------+------------+
|                                        | time (kde mode)                         | memory                       |
+----------------------------------------+--------------------+--------------------+-----------------+------------+
| subject                                | Tag: <current>     | Tag: base          | Tag: <current>  | Tag: base  |
+----------------------------------------+--------------------+--------------------+-----------------+------------+
| benchLoad10000EventsMissingSnapshot () | 161.391ms (±0.00%) | 163.442ms (±0.00%) | 38.652mb        | 38.646mb   |
| benchLoad10000Events ()                | 513.900μs (±0.00%) | 527.900μs (±0.00%) | 38.652mb        | 38.646mb   |
+----------------------------------------+--------------------+--------------------+-----------------+------------+

SimpleSetupBench
================

+----------------------------------------+--------------------+--------------------+-----------------+------------+
|                                        | time (kde mode)                         | memory                       |
+----------------------------------------+--------------------+--------------------+-----------------+------------+
| subject                                | Tag: <current>     | Tag: base          | Tag: <current>  | Tag: base  |
+----------------------------------------+--------------------+--------------------+-----------------+------------+
| benchLoad10000Events ()                | 159.044ms (±0.00%) | 157.291ms (±0.00%) | 38.655mb        | 38.649mb   |
| benchSave1Event ()                     | 930.300μs (±0.00%) | 998.800μs (±0.00%) | 38.655mb        | 38.649mb   |
| benchSave10000Events ()                | 474.299ms (±0.00%) | 493.616ms (±0.00%) | 38.921mb        | 38.916mb   |
| benchSave10000Aggregates ()            | 9.817s (±0.00%)    | 9.630s (±0.00%)    | 38.655mb        | 38.649mb   |
| benchSave10000AggregatesTransaction () | 7.440s (±0.00%)    | 7.519s (±0.00%)    | 38.655mb        | 38.649mb   |
+----------------------------------------+--------------------+--------------------+-----------------+------------+

SplitStreamBench
================

+-------------------------+--------------------+--------------------+-----------------+------------+
|                         | time (kde mode)                         | memory                       |
+-------------------------+--------------------+--------------------+-----------------+------------+
| subject                 | Tag: <current>     | Tag: base          | Tag: <current>  | Tag: base  |
+-------------------------+--------------------+--------------------+-----------------+------------+
| benchLoad10000Events () | 5.563ms (±0.00%)   | 5.597ms (±0.00%)   | 42.520mb        | 42.514mb   |
| benchSave10000Events () | 631.875ms (±0.00%) | 662.200ms (±0.00%) | 42.797mb        | 42.792mb   |
+-------------------------+--------------------+--------------------+-----------------+------------+

ProjectionistBench
==================

+---------------------------+-----------------+-----------------+-----------------+------------+
|                           | time (kde mode)                   | memory                       |
+---------------------------+-----------------+-----------------+-----------------+------------+
| subject                   | Tag: <current>  | Tag: base       | Tag: <current>  | Tag: base  |
+---------------------------+-----------------+-----------------+-----------------+------------+
| benchHandle10000Events () | 3.255s (±0.00%) | 3.297s (±0.00%) | 39.054mb        | 39.049mb   |
+---------------------------+-----------------+-----------------+-----------------+------------+

This comment gets update everytime a new commit comes in!