remove explicit branch in .gitmodules, only the SHA in workspace index matters

.gitmodules

@@ -1,47 +1,36 @@
 [submodule "LoopKit"]
 	path = LoopKit
 	url = https://github.com/loopandlearn/LoopKit.git
-	branch = trio
 [submodule "CGMBLEKit"]
 	path = CGMBLEKit
 	url = https://github.com/loopandlearn/CGMBLEKit.git
-	branch = trio
 [submodule "dexcom-share-client-swift"]
 	path = dexcom-share-client-swift
 	url = https://github.com/loopandlearn/dexcom-share-client-swift.git
-	branch = trio
 [submodule "RileyLinkKit"]
 	path = RileyLinkKit
 	url = https://github.com/loopandlearn/RileyLinkKit
-	branch = trio
 [submodule "OmniBLE"]
 	path = OmniBLE
 	url = https://github.com/loopandlearn/OmniBLE.git
-	branch = trio
 [submodule "G7SensorKit"]
 	path = G7SensorKit
 	url = https://github.com/loopandlearn/G7SensorKit.git
-	branch = trio
 [submodule "OmniKit"]
 	path = OmniKit
 	url = https://github.com/loopandlearn/OmniKit.git
-	branch = trio
 [submodule "MinimedKit"]
 	path = MinimedKit
 	url = https://github.com/loopandlearn/MinimedKit.git
-	branch = trio
 [submodule "LibreTransmitter"]
 	path = LibreTransmitter
 	url = https://github.com/loopandlearn/LibreTransmitter.git
-	branch = trio
 [submodule "TidepoolService"]
 	path = TidepoolService
 	url = https://github.com/loopandlearn/TidepoolService.git
-	branch = trio
 [submodule "DanaKit"]
 	path = DanaKit
 	url = https://github.com/loopandlearn/DanaKit
 [submodule "MedtrumKit"]
 	path = MedtrumKit
-	branch = dev
 	url = https://github.com/loopandlearn/MedtrumKit