Add lint action for PR title length (#2481)

This enforces some basic restrictions on PR titles as good commit titles.

Tested: https://github.com/google/iree/pull/2481/checks?check_run_id=859804845 gave a nice failure

.github/workflows/lint.yml

diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 45cf1bd..d8eeecf 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -66,6 +66,14 @@
         with:
           strict: true
 
+  pr-title-length:
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: deepakputhraya/action-pr-title@v1.0.0
+        with:
+          min_length: 5
+          max_length: 80
+
   buildifier:
     runs-on: ubuntu-18.04
     steps: