Bump Navigation to 2.6.0-beta01

Test: ./gradlew bOS
Change-Id: I620c4f13e0f392327c57a77cd119c0f80a72a148
diff --git a/navigation/navigation-runtime-ktx/api/restricted_2.6.0-beta01.txt b/navigation/navigation-runtime-ktx/api/restricted_2.6.0-beta01.txt
new file mode 100644
index 0000000..e6f50d0
--- /dev/null
+++ b/navigation/navigation-runtime-ktx/api/restricted_2.6.0-beta01.txt
@@ -0,0 +1 @@
+// Signature format: 4.0