Support PHP 8.5

[emyller]

Users cannot install flagsmith-php-client 5.0.0 on PHP 8.5.

The dependency softcreatr/jsonpath:^0.10.0 constrains PHP to versions 8.1–8.4. The upstream repository has updated the constraint to include PHP 8.5 on their main branch, but no release exists yet.

Acceptance criteria

• Users install flagsmith-php-client 5.0.0 on PHP 8.5

[emyller]

Upstream issue opened: SoftCreatR/JSONPath#82

[SoftCreatR]

Done :)-