Bazel: Bump bazel version to 1.0.0rc2

Given this severe security vulnerability in Bazel 0.29: [1] we prefer
to upgrade to 1.0.0rc2, even though it is a release candidate and not
officially released Bazel version.

This effectively forces users to either download this release
candidate manually from this loation: [2], or use bazelisk if they are
not already, since this RC version is not included in regular package
managers yet.

[1] bazelbuild/bazel#9327
[2] https://releases.bazel.build/1.0.0/rc2/index.html

Change-Id: I7d4121a145450f0d8687b239db3afa14f2dc0785

.bazelversion

@@ -1,2 +1 @@
-0.29.0
-
+1.0.0rc2