CI: use t2a-standard-8

.github/workflows/verible-ci.yml

diff --git a/.github/workflows/verible-ci.yml b/.github/workflows/verible-ci.yml
index a3ce48f..d40b2d8 100644
--- a/.github/workflows/verible-ci.yml
+++ b/.github/workflows/verible-ci.yml
@@ -11,7 +11,7 @@
 env:
   BOT_USER: "Deployment Bot"
   BOT_EMAIL: "verible-dev@googlegroups.com"
-  GHA_MACHINE_TYPE: "n2-standard-8"
+  GHA_MACHINE_TYPE: "t2a-standard-8"
   DEBIAN_FRONTEND: "noninteractive"
   VERIBLE_BINDIR: "/tmp/verible-bin"