Update CI config

.github/workflows/linux.yml

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index d56d257..fce0d71 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -1,6 +1,6 @@
 name: linux
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
   build:

.github/workflows/macos.yml

diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 75ae194..33be500 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -1,6 +1,6 @@
 name: macos
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
   build:

.github/workflows/windows.yml

diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index 088ffc7..1fc3689 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -1,6 +1,6 @@
 name: windows
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
   build: