Rename Bazel files to have `.bazel` extensions.

BUILD.bazel

diff --git a/BUILD b/BUILD.bazel
similarity index 100%
rename from BUILD
rename to BUILD.bazel

README.md

diff --git a/README.md b/README.md
index 3dfe5f3..e36230d 100644
--- a/README.md
+++ b/README.md
@@ -30,7 +30,7 @@
 # We still require the pybind library.
 http_archive(
   name = "pybind11",
-  build_file = "@pybind11_bazel//:pybind11.BUILD",
+  build_file = "@pybind11_bazel//:pybind11-BUILD.bazel",
   strip_prefix = "pybind11-<version>",
   urls = ["https://github.com/pybind/pybind11/archive/v<version>.zip"],
 )

WORKSPACE.bazel

diff --git a/WORKSPACE b/WORKSPACE.bazel
similarity index 100%
rename from WORKSPACE
rename to WORKSPACE.bazel

WORKSPACE.bzlmod

diff --git a/WORKSPACE b/WORKSPACE.bzlmod
similarity index 100%
copy from WORKSPACE
copy to WORKSPACE.bzlmod

internal_configure.bzl

diff --git a/internal_configure.bzl b/internal_configure.bzl
index a6b15e1..b569f6b 100644
--- a/internal_configure.bzl
+++ b/internal_configure.bzl
@@ -19,7 +19,7 @@
     version = version.split(".bzl.")[0]
     http_archive(
         name = "pybind11",
-        build_file = "//:pybind11.BUILD",
+        build_file = "//:pybind11-BUILD.bazel",
         strip_prefix = "pybind11-%s" % version,
         urls = ["https://github.com/pybind/pybind11/archive/v%s.zip" % version],
     )

pybind11-BUILD.bazel

diff --git a/pybind11.BUILD b/pybind11-BUILD.bazel
similarity index 100%
rename from pybind11.BUILD
rename to pybind11-BUILD.bazel