update dependabot to preserve intended versions (#215)

### What changes are you making?

Updates the Dependabot configuration to allow Kotlin compiler/plugin updates up to (but not including) 3.0.0, reflecting that the project now builds with a 2.x compiler. A separate ignore rule is added for `kotlin-stdlib` to cap it at 2.1.0, keeping the published stdlib dependency aligned with the Kotlin API/language consumer floor rather than the newer compiler version used to build the AAR. These rules are applied consistently across both the library and sample app Dependabot configurations.

### How to test

Verify that Dependabot does not propose updates to `org.jetbrains.kotlin.*` at 3.0.0 or above, and does not propose updates to `org.jetbrains.kotlin:kotlin-stdlib` at 2.1.0 or above.

---

### Before you merge

> [!IMPORTANT]
> - [ ] I've added tests to support my implementation
> - [x] I have read and agree with the [Contribution Guidelines](./CONTRIBUTING.md)
> - [x] I have read and agree with the [Code of Conduct](./CODE_OF_CONDUCT.md)
> - [ ] I've updated the relevant platform README (`platforms/swift/README.md` and/or `platforms/android/README.md`)

---

<details>
<summary>Releasing a new Swift version?</summary>

- [ ] I have bumped the version in `ShopifyCheckoutKit.podspec`
- [ ] I have bumped the version in `platforms/swift/Sources/ShopifyCheckoutKit/ShopifyCheckoutKit.swift`
- [ ] I have updated `platforms/swift/CHANGELOG.md`
- [ ] I have updated the SwiftPM/CocoaPods version snippets in `platforms/swift/README.md` (major version only)

</details>

<details>
<summary>Releasing a new Android version?</summary>

- [ ] I have bumped the `versionName` in `platforms/android/lib/build.gradle`
- [ ] I have updated `platforms/android/CHANGELOG.md`
- [ ] I have updated the Gradle/Maven version snippets in `platforms/android/README.md`

</details>

> [!TIP]
> See the [Contributing documentation](./CONTRIBUTING.md) for the full release process per platform.

Author: kiftio

.github/dependabot.yml

@@ -23,9 +23,14 @@ updates:
     cooldown:
       default-days: 7
     ignore:
-      # Keep Kotlin on 1.9.x for compatibility
+      # Keep Kotlin compiler/plugin updates on 2.x unless the consumer floor is
+      # deliberately re-evaluated.
       - dependency-name: "org.jetbrains.kotlin.*"
-        versions: [">=2.0.0"]
+        versions: [">=3.0.0"]
+      # Keep the published stdlib dependency aligned with the Kotlin API/language
+      # consumer floor, not the newer compiler used to build the AAR.
+      - dependency-name: "org.jetbrains.kotlin:kotlin-stdlib"
+        versions: [">=2.1.0"]
       # Keep kotlinx-serialization on 1.7.x while the library's Kotlin API/language
       # consumer floor is pinned to 2.0.
       - dependency-name: "org.jetbrains.kotlinx:kotlinx-serialization-json"
@@ -48,9 +53,14 @@ updates:
     ignore:
       # The sample includes the Android library as :lib, so library dependencies can
       # appear in this Dependabot scan too.
-      # Keep Kotlin on 1.9.x for compatibility
+      # Keep Kotlin compiler/plugin updates on 2.x unless the consumer floor is
+      # deliberately re-evaluated.
       - dependency-name: "org.jetbrains.kotlin.*"
-        versions: [">=2.0.0"]
+        versions: [">=3.0.0"]
+      # Keep the published stdlib dependency aligned with the Kotlin API/language
+      # consumer floor, not the newer compiler used to build the AAR.
+      - dependency-name: "org.jetbrains.kotlin:kotlin-stdlib"
+        versions: [">=2.1.0"]
       # Keep kotlinx-serialization on 1.7.x while the library's Kotlin API/language
       # consumer floor is pinned to 2.0.
       - dependency-name: "org.jetbrains.kotlinx:kotlinx-serialization-json"