[JUJU-1017] Release 2.9.9 notes

[cderici]

What's Changed

• JUJU-835 Avoid ignoring asyncio exceptions in coroutines by @cderici in [JUJU-835] Avoid ignoring asyncio exceptions in coroutines #658
• JUJU-843 Attach-resource to check if given binary file by @cderici in [JUJU-843] Attach-resource to check if given binary file #659
• JUJU-858 Add quality of life feature ensure application removal at return by @cderici in [JUJU-858] Add quality of life feature ensure application removal at return #665
• JUJU-965 Add a bit of client side constraint validation by @cderici in [JUJU-965] Add a bit of client side constraint validation #666
• support python3.10 with later versions of websockets by @addyess in support python3.10 with later versions of websockets #673
• Revert "Avoid ignoring asyncio exceptions in coroutines" by @simskij in Revert "Avoid ignoring asyncio exceptions in coroutines" #672
• JUJU-796 Add relate method and deprecate add-relation by @jack-w-shaw in [JUJU-796] Add relate method and deprecate add-relation #660
• JUJU-981 Get series from deployed app instead of metadata when charm upgrade by @cderici in [JUJU-981] Get series from deployed app instead of metadata when charm upgrade #671

[juanmanuel-tirado]

LG2M