deps: Run pod update sqlite3 to resolve pod install error

[chrisbobbe]

In f28dd0b, we upgraded the Dart package sqlite3_flutter_libs past simolus3/sqlite3.dart@c16721003, which bumped the version of the sqlite3 pod published on CocoaPods (not to be confused with the Dart package with that same name on pub.dev).

So in flutter run targeting an iOS device, the pod install step would fail with output including the following:

    [!] CocoaPods could not find compatible versions for pod "sqlite3":
      In snapshot (Podfile.lock):
        sqlite3 (= 3.41.0, ~> 3.41.0)

      In Podfile:
        sqlite3_flutter_libs (from `.symlinks/plugins/sqlite3_flutter_libs/ios`) was resolved to 0.0.1, which depends on
          sqlite3 (~> 3.41.2)

    You have either:
     * out-of-date source repos which you can update with `pod repo update` or with `pod install --repo-update`.
     * changed the constraints of dependency `sqlite3` inside your development pod `sqlite3_flutter_libs`.
       You should run `pod update sqlite3` to apply changes you've made.

Flutter then gave its own output, along the lines of just that first bullet point:

Error: CocoaPods's specs repository is too out-of-date to satisfy dependencies.
To update the CocoaPods specs, run:
  pod repo update

Exception: Error running pod install

But actually, after studying both bullet points and trying their suggested fixes, it turns out the second one is right. So, follow it here by running pod update sqlite3.

[chrisbobbe]

Closing, as #148 was merged, superseding this.