test: add pull request event for valid PR

Author: matmar10

test/valid-pr.json

@@ -0,0 +1,16 @@
+{
+  "pull_request": {
+    "head": {
+      "ref": "sample-head-ref"
+    },
+    "base": {
+      "ref": "sample-base-ref"
+    }
+  },
+  "repository": {
+    "name": "pr-conventional-commit",
+    "owner": {
+      "login": "matmar10"
+    }
+  }
+}