Reset the Bzlmod compatibility level to 1.

In bazelbuild/bazel-central-registry#806,
I agreed to decouple the compatibility level from the `SONAME` as
there are generally no ABI concerns when building RE2 with Bazel.

Change-Id: I4c90a440c7e9ce364110574c4ce17d0ee15696b7
Reviewed-on: https://code-review.googlesource.com/c/re2/+/61730
Reviewed-by: Alex Chernyakhovsky <achernya@google.com>
Reviewed-by: Paul Wankadia <junyer@google.com>

MODULE.bazel

@@ -7,7 +7,7 @@
 module(
     name = "re2",
     version = "2023-08-01",
-    compatibility_level = 11,
+    compatibility_level = 1,
 )
 
 bazel_dep(name = "platforms", version = "0.0.7")