Submit 5.3.0 to CRAN

[anashen]

Final updates before submitting SeuratObject v5.3.0 to CRAN 🚀

• Bump version
• Finalize changelog
• Pre-Release Checks
• Reverse Dependency Checks
• win-builder (R-release, R-devel, R-oldrel)
• macOS builder (R-release, R-devel) (macbuilder is down but verified build & check on local macOS)
• Update CRAN comments

[anashen]

Commits were added as hotfixes to 5.3-stable and this branch to address R CMD check warnings/errors that did not arise during routine testing.

All but one of these fixes relate to deprecation warnings in the package's test files & roxygen examples. Commit 9da5671 was made to avoid the NOTE "Examples with CPU or elapsed time > 5s".

[anashen]

• win-builder gives no new NOTEs, WARNINGs, or ERRORs
• mac-builder is down ("The macOS package build services are currently not responding. Please try again later.")
  • local macOS build passes R CMD check --as-cran with no new N/W/E

[anashen]

Reverse dependency checks give ERRORs on the now-defunct "slot" argument of GetAssayData and SetAssayData (initially deprecated in v5.0.0).

From https://github.com/satijalab/seurat-object/actions/runs/20117541914/job/57736830494:

                  ERROR   WARNING NOTE OK
  Source packages     0       0    1  0
  Reverse depends     6       2    7 12

• examples in Platypus
• tests in SCpubr
• examples and tests in Seurat
• vignettes in XYomics
• examples and vignettes in scpoisson