CakePHP 5.x support (#18)

* upgrade to cakephp 5.x

* Geometry tests

* GeometryType tests

* fix codesniffer errors in GeometryBehavior

* fix phpstan errors

* require only cakephp orm

Add decorator method for Geometry conversion (#17)

* Add decorator method for Geometry convertion

* Update src/Database/Type/GeometryType.php

Co-authored-by: Paolo Cuffiani <paolo.cuffiani@gmail.com>

* Update src/Database/Type/GeometryType.php

Co-authored-by: Paolo Cuffiani <paolo.cuffiani@gmail.com>

* Update src/Database/Type/GeometryType.php

Co-authored-by: Paolo Cuffiani <paolo.cuffiani@gmail.com>

* Fix cs and stan issues

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Co-authored-by: Paolo Cuffiani <paolo.cuffiani@gmail.com>

Merge pull request #7 from chialab/chore/add-mixed-return-type

Add `mixed` return type to `jsonSerialize`

Merge pull request #5 from chialab/add-contains-improve-mysql-wkb-filter

fix serializeAs initialization

Merge pull request #4 from chialab/serialize-as-method

Add `serializeAs` property

Merge pull request #3 from chialab/geometry-behavior

Introducing the Geometry behavior

Merge pull request #1 from chialab/relax-cakephp-constraint

Relax cakephp constraint

fix: fix namespace to comply with PSR-4