set workflow trigger condition to manually

Signed-off-by: Double Sine <xiao_ai_yu@live.cn>

.github/workflows/build.yml

@@ -1,10 +1,9 @@
 name: navicat-keygen builds
-on: [push]
+on: workflow_dispatch
 
 jobs:
   navicat-keygen-x86:
     runs-on: windows-latest
-    if: "startsWith(github.event.head_commit.message, '[build]')"
     steps:
       - name: Install dependencies
         run: |
@@ -33,7 +32,6 @@ jobs:
 
   navicat-keygen-x64:
     runs-on: windows-latest
-    if: "startsWith(github.event.head_commit.message, '[build]')"
     steps:
       - name: Install dependencies
         run: |