fix: size diff job (#413)

## 📜 Description

Fixed "0 bytes" diff from size-diff job report.

## 💡 Motivation and Context

It was incorrect metric. Such metric is totally useless.

The original problem was the fact that in new node `18.20.1` prints
output gathered from `react-native-builder-bob`:

```bash
> react-native-keyboard-controller@1.11.6 prepare
> bob build

ℹ Building target commonjs
ℹ Cleaning up previous build at lib/commonjs
ℹ Compiling 32 files in src with babel
✔ Wrote files to lib/commonjs
ℹ Building target module
ℹ Cleaning up previous build at lib/module
ℹ Compiling 32 files in src with babel
✔ Wrote files to lib/module
ℹ Building target typescript
ℹ Cleaning up previous build at lib/typescript
ℹ Generating type definitions with tsc
```

And such output can not be parsed.

The interesting thing is that `18.19.0` version produced expected
result. So in this PR I locked node version for this particular job.

## 📢 Changelog

<!-- High level overview of important changes -->
<!-- For example: fixed status bar manipulation; added new types
declarations; -->
<!-- If your changes don't affect one of platform/language below - then
remove this platform/language -->

### CI

- lock node to `18.19.0` for `size-diff` job;

## 🤔 How Has This Been Tested?

Tested on CI.

## 📸 Screenshots (if appropriate):

<img width="913" alt="image"
src="https://github.com/kirillzyusko/react-native-keyboard-controller/assets/22820318/e2dc190d-9d27-4e8e-b3df-cb60a954a9b4">

## 📝 Checklist

- [x] CI successfully passed
- [x] I added new mocks and corresponding unit-tests if library API was
changed

Author: kirillzyusko

.github/workflows/size-diff.yml

@@ -18,6 +18,10 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ github.event.pull_request.base.ref }}
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 18.19.0
+          cache: yarn
       - name: Install dependencies
         run: yarn install --frozen-lockfile
       - name: Calculate size of package (target)
@@ -26,6 +30,8 @@ jobs:
       - uses: actions/checkout@v4
       - name: Install dependencies
         run: yarn install --frozen-lockfile
+      - name: Pack
+        run: npm pack --json
       - name: Calculate size of package (current)
         id: new-size
         run: echo "NEW_SIZE=$(node scripts/size.js)" >> "$GITHUB_OUTPUT"