Update dartdoc to 0.17.1+1 for flutter (#15522)

dev/bots/docs.sh

diff --git a/dev/bots/docs.sh b/dev/bots/docs.sh
index c2cfe6b..29afcac 100755
--- a/dev/bots/docs.sh
+++ b/dev/bots/docs.sh
@@ -21,7 +21,7 @@
 fi
 
 # Install dartdoc.
-bin/cache/dart-sdk/bin/pub global activate dartdoc 0.17.0
+bin/cache/dart-sdk/bin/pub global activate dartdoc 0.17.1+1
 
 # This script generates a unified doc set, and creates
 # a custom index.html, placing everything into dev/docs/doc.