[Infra] Fix Firestore source build privacy manifest SPM warnings (#15076)

Author: ncooke3

Package.swift

@@ -1469,6 +1469,7 @@ func firestoreTargets() -> [Target] {
           "Protos/protos/",
           "README.md",
           "Source/CMakeLists.txt",
+          "Source/Resources/",
           "Swift/",
           "core/CMakeLists.txt",
           "core/src/util/config_detected.h.in",
@@ -1527,6 +1528,7 @@ func firestoreTargets() -> [Target] {
           "Protos/",
           "README.md",
           "Source/",
+          "Swift/Source/Resources/",
           "core/",
           "fuzzing/",
           "test.sh",