3.20.0

This reverts commit 11de748.

(cherry picked from commit 58e320a)

All synthetic methods implemented by `method_missing` are now supported by `respond_to?`.

Fixes issue #9202.

* Fix null pointer exceptions exposed by new regression tests.
* Fix clear_ on oneofs so that it is safe to call repeatedly and so that respond_to? does not depend on whether the oneof is currently cleared.
* Code cleanup: reenable more tests on JRuby.
* Align JRuby behavior with CRuby by throwing a RuntimeError when attempting to assign to a oneof.

(cherry picked from commit 8e7f936)

Cherry pick JRuby changes that fix NPE during encoding (#9507) and implements respond_to? (#9202) into 3.20.x.

Fix building packaged PHP extension

(cherry picked from commit 7f9901c)

@jtattermusch @mkruskal-google

(cherry picked from commit 55177c3)

@mrkruskal

(cherry picked from commit 88eb755)

#9788)

* Add breaking change (disallow setting numpy singleton arrays and multi-dimensional arrays to fields/repeated fields) and fix to CHANGES.txt, which was missed in a previous git sync.

See #9804 for details.

* move composer.json out of root to avoid confusion

* fix: update php deployed json

* Update protobuf version

* Updated Makefile.am for composer.json move.

* Update protobuf version

* Updated Makefile.am for composer.json move.

* Updated CHANGES.txt for 3.20.1.

* Fixed spelling.

Previously it was releasing content from main/master, not the
release branch!

I fixed this by not checking out a separate copy of protobuf.
Also updated the composer.json so we don't need to rewrite it with
sed.

Fixed PHP release script.