prompt: update powerlevel10k submodule to the latest commit (sorin-ionescu#1717)

romkatv · evanrs · commit 1ea118906614 · 2021-08-06T20:28:42.000-04:00
A bunch of bug fixes. Most notably romkatv/powerlevel10k#89.
diff --git a/modules/prompt/external/powerlevel10k b/modules/prompt/external/powerlevel10k
@@ -1 +1 @@
-Subproject commit 31fdb6797ed19f008f25e26e452e297981295410
+Subproject commit 613ffec4b61fc8c97427a99bcca72808a980645e
