CompatHelper: bump compat for "DocStringExtensions" to "0.9" (#404)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Chris Elrod <elrodc@gmail.com>

Author: github-actions[bot]

Project.toml

@@ -33,7 +33,7 @@ ArrayInterfaceStaticArrays = "0.1.2"
 CPUSummary = "0.1.3 - 0.1.8, 0.1.11"
 ChainRulesCore = "1"
 CloseOpenIntervals = "0.1.2"
-DocStringExtensions = "0.8"
+DocStringExtensions = "0.8, 0.9"
 ForwardDiff = "0.9, 0.10"
 HostCPUFeatures = "0.1.3"
 IfElse = "0.1"