chore(deps): update dependency firebase/firebase-ios-sdk to from: "10.15.0" (#584)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
|
[firebase/firebase-ios-sdk](https://togithub.com/firebase/firebase-ios-sdk)
| minor | `from: "10.14.0"` -> `from: "10.15.0"` |

---

### Release Notes

<details>
<summary>firebase/firebase-ios-sdk (firebase/firebase-ios-sdk)</summary>

###
[`v10.15.0`](https://togithub.com/firebase/firebase-ios-sdk/releases/tag/10.15.0):
Firebase Apple 10.15.0

[Compare
Source](https://togithub.com/firebase/firebase-ios-sdk/compare/10.14.0...10.15.0)

The Firebase Apple SDK (10.15.0) is now available. For more details, see
the [Firebase Apple SDK release
notes.](https://firebase.google.com/support/release-notes/ios#10.15.0)

To install this SDK, see [Add Firebase to your
project.](https://firebase.google.com/docs/ios/setup)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined),
Automerge - At any time (no schedule defined).

🚦 **Automerge**: Enabled.

♻ **Rebasing**: Whenever PR is behind base branch, or you tick the
rebase/retry checkbox.

👻 **Immortal**: This PR will be recreated if closed unmerged. Get
[config help](https://togithub.com/renovatebot/renovate/discussions) if
that's undesired.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR has been generated by [Renovate
Bot](https://togithub.com/renovatebot/renovate).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzNi45My4wIiwidXBkYXRlZEluVmVyIjoiMzYuOTMuMCIsInRhcmdldEJyYW5jaCI6Im1haW4ifQ==-->

Co-authored-by: Self-hosted Renovate Bot <361546+cgrindel-self-hosted-renovate[bot]@users.noreply.github.enterprise.com>

Author: cgrindel-self-hosted-renovate[bot]

examples/firebase_example/Package.resolved

@@ -5,7 +5,7 @@ import PackageDescription
 let package = Package(
     name: "firebase_example",
     dependencies: [
-        .package(url: "https://github.com/firebase/firebase-ios-sdk", .upToNextMajor(from: "10.14.0")),
+        .package(url: "https://github.com/firebase/firebase-ios-sdk", .upToNextMajor(from: "10.15.0")),
         // Used by crashlytics example
         .package(url: "https://github.com/ashleymills/Reachability.swift.git", .upToNextMajor(from: "5.1.0")),
     ]

examples/firebase_example/Package.swift

@@ -1548,9 +1548,9 @@
       "name": "swiftpkg_firebase_ios_sdk",
       "identity": "firebase-ios-sdk",
       "remote": {
-        "commit": "2bfe6abe1014aafe5cf28401708f7d39f9926a76",
+        "commit": "8a8ec57a272e0d31480fb0893dda0cf4f769b57e",
         "remote": "https://github.com/firebase/firebase-ios-sdk",
-        "version": "10.14.0"
+        "version": "10.15.0"
       }
     },
     {