[platform_versioning] Add placeholder platform_version.json file

This file is needed to test api-level-roller.

Bug: 119267
Change-Id: I83d9bb373163cff0025d18d2cadbe9cd8308dcc9
Reviewed-on: https://fuchsia-review.googlesource.com/c/infra/roller-tests/integration/+/793401
Fuchsia-Auto-Submit: Anthony Fandrianto <atyfto@google.com>
Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>
Reviewed-by: Oliver Newman <olivernewman@google.com>
diff --git a/infra/config/common/platform_version.json b/infra/config/common/platform_version.json
new file mode 100644
index 0000000..9df3296
--- /dev/null
+++ b/infra/config/common/platform_version.json
@@ -0,0 +1,7 @@
+{
+    "in_development_api_level": 3,
+    "supported_fuchsia_api_levels": [
+        1,
+        2
+    ]
+}