lock submodules to version + move from stb to stb_sprintf

.gitmodules

@@ -1,12 +1,14 @@
 [submodule "External/Imgui"]
 	path = External/Imgui
 	url = https://github.com/ocornut/imgui.git
+	# Pinned to v1.93.0 (c1aaac65e)
+
 [submodule "Juliet/external/xxHash"]
 	path = Juliet/external/xxHash
 	url = https://github.com/Cyan4973/xxHash.git
-[submodule "Juliet/Juliet/external/stb"]
-	path = Juliet/Juliet/external/stb
-	url = https://github.com/nothings/stb.git
+	# Pinned to v0.8.4 (c87183a77)
+
 [submodule "Juliet/external/stb_sprintf"]
 	path = Juliet/external/stb_sprintf
 	url = https://github.com/nothings/stb_sprintf.git
+	# Pinned to v1.10 / commit 2ffb3379e