ci(tests) Trigger on workflow_dispatch for codspeed

`workflow_dispatch` allows CodSpeed to trigger backtest performance
analysis in order to generate initial data.

See also: https://docs.codspeed.io/ci/github-actions#2-create-the-benchmarks-workflow

Author: tony

.github/workflows/tests.yml

@@ -10,6 +10,8 @@ on:
   pull_request:
     branches:
       - '**'
+  # `workflow_dispatch` allows CodSpeed to trigger backtest performance analysis in order to generate initial data.
+  workflow_dispatch:
 
 jobs:
   build: