DOC/BLD: v1.18.0 release notes, update dependencies

[ZLLentz]

Description

• Run the docs script that @tangkong added in MNT: update lightpath use for object database loading #350
• Add my info from prior to those scripts
• Reclassify lightpath update as a feature
• Require python 3.9, lightpath 1.0.1

Motivation and Context

• Get a tag out for conda env
• lightpath update is a pretty big deal, even if the line count was low here, so I thought it deserved more than a bugfix number
• 3.9 is required for pcdsdevices anyway, lightpath 1.0.1 is the reality of MNT: update lightpath use for object database loading #350

How Has This Been Tested?

• Hopefully the tests still pass

Where Has This Been Documented?

• This is docs

[tangkong]

We should change the pip-requirements too right? pcdsdevices at least should get bumped, and maybe lightpath is available on pypi now?

[ZLLentz]

Good call, I completely forgot

[ZLLentz]

Is this correct now?

[ZLLentz]

@tangkong we good to go for the tag?

[tangkong]

Looks good to me 👍