CI: Update Ruby and PostgreSQL

Signed-off-by: Takuro Ashie <ashie@clear-code.com>

Author: ashie

.github/workflows/linux.yml

@@ -1,7 +1,9 @@
 name: linux
 on:
-  - push
-  - pull_request
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
 
 jobs:
   build:
@@ -10,30 +12,34 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ '2.5', '2.6', '2.7', '3.0' ]
-        postgres: [ '9', '10', '11', '12', '13' ]
+        ruby: [ '3.1', '3.0', '2.7', '2.6' ]
+        postgres: [ '14', '13', '12', '11', '10', '9' ]
         os:
           - ubuntu-latest
         experimental: [false]
         include:
           - ruby: head
-            postgres: '9'
+            postgres: '14'
             os: ubuntu-latest
             experimental: true
           - ruby: head
-            postgres: '10'
+            postgres: '13'
+            os: ubuntu-latest
+            experimental: true
+          - ruby: head
+            postgres: '12'
             os: ubuntu-latest
             experimental: true
           - ruby: head
             postgres: '11'
             os: ubuntu-latest
             experimental: true
           - ruby: head
-            postgres: '12'
+            postgres: '10'
             os: ubuntu-latest
             experimental: true
           - ruby: head
-            postgres: '13'
+            postgres: '9'
             os: ubuntu-latest
             experimental: true
     services: