Change Firestore external ref to one with patch.exe bugfix (#1006)

In the Firestore iOS SDK, the usage of patch.exe crashes on Windows due to CRLF issues. This is fixed in that repo by firebase/firebase-ios-sdk#9941; use that commit in the C++ SDK, since it was not included in the 9.2.0 release. (The commit was branched off of the CocoaPods-9.2.0 tag.)

Author: jonsimantov

cmake/external/firestore.cmake

@@ -20,7 +20,7 @@ endif()
 
 # If the format of the line below changes, then be sure to update
 # https://github.com/firebase/firebase-cpp-sdk/blob/fd054fa016/.github/workflows/update-dependencies.yml#L81
-set(version CocoaPods-9.2.0)
+set(version 632ea8c18bf78fa67bc63d3f32015a976d8caa44)
 
 function(GetReleasedDep)
   message("Getting released firebase-ios-sdk @ ${version}")