Update Package.swift for CI. (#9297)

Update GoogleAppMeasurement for CI

Author: granluo

.github/workflows/functions.yml

@@ -45,6 +45,8 @@ jobs:
     # Don't run on private repo unless it is a PR.
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request'
     runs-on: macos-11
+    env:
+      FIREBASECI_USE_LATEST_GOOGLEAPPMEASUREMENT: 1
     steps:
     - uses: actions/checkout@v2
     - uses: mikehardy/buildcache-action@50738c6c77de7f34e66b870e4f8ede333b69d077

Package.swift

@@ -16,6 +16,7 @@
 // limitations under the License.
 
 import PackageDescription
+import class Foundation.ProcessInfo
 
 let firebaseVersion = "8.12.0"
 
@@ -1195,3 +1196,14 @@ let package = Package(
   cLanguageStandard: .c99,
   cxxLanguageStandard: CXXLanguageStandard.gnucxx14
 )
+
+if ProcessInfo.processInfo.environment["FIREBASECI_USE_LATEST_GOOGLEAPPMEASUREMENT"] != nil {
+  if let GoogleAppMeasurementIndex = package.dependencies
+    .firstIndex(where: { $0.name == "GoogleAppMeasurement" }) {
+    package.dependencies[GoogleAppMeasurementIndex] = .package(
+      name: "GoogleAppMeasurement",
+      url: "https://github.com/google/GoogleAppMeasurement.git",
+      .branch("main")
+    )
+  }
+}