[infra] Fix tools/bots/find_base_commit.dart.

Broken in dd5b9cd7d74e38e0f2a76c08dfa365808b04b7ed.

Change-Id: I2b3fd26c22d6e8d4266611809da84a2726346446
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/377726
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>

tools/analysis_options.yaml

diff --git a/tools/analysis_options.yaml b/tools/analysis_options.yaml
index d7f57b2..9fbde89 100644
--- a/tools/analysis_options.yaml
+++ b/tools/analysis_options.yaml
@@ -13,7 +13,6 @@
 
 linter:
   rules:
-    - avoid_dynamic_calls
     - comment_references
     - depend_on_referenced_packages
     - directives_ordering

tools/bots/find_base_commit.dart

diff --git a/tools/bots/find_base_commit.dart b/tools/bots/find_base_commit.dart
index 2765baf..73dcfda 100755
--- a/tools/bots/find_base_commit.dart
+++ b/tools/bots/find_base_commit.dart
@@ -100,7 +100,7 @@
   // can, the first time we see a commit, we know it's newer than all commits
   // we haven't seen yet. The insertion order into the buildersForCommits map
   // will then sorted with the newest commit first.
-  final builds = searchResult["builds"] as List<Map>?;
+  final builds = searchResult["builds"] as List?;
   if (builds == null) {
     print("No builds found");
     exit(1);