Fix some debian metadata

Without ca-certificates, we cannot fetch bazel from https.

We also conflict with bazel-bootstrap due to /usr/bin/bazel.

deb/BUILD

@@ -36,7 +36,8 @@ ARCHES = ["amd64", "arm64"]
     pkg_deb(
         name = "bazelisk-{}_deb".format(arch),
         architecture = arch,
-        conflicts = ["bazel"],
+        depends = ["ca-certificates"],
+        conflicts = ["bazel", "bazel-bootstrap"],
         data = ":bazelisk-{}_tar".format(arch),
         description_file = ":description.txt",
         homepage = "https://github.com/bazelbuild/bazelisk",