Add GHA job to run memory leak tests

We don't run them on Windows because we know the memory measurement code
currently runs only on Unix. We can tackle that separately though.

Signed-off-by: Rodrigo Tobar <rtobar@icrar.org>

.github/workflows/memleak-tests.yml

@@ -0,0 +1,47 @@
+name: Run memory leak tests
+
+# Build on every branch push, tag push, and pull request change:
+on:
+  push:
+  pull_request:
+  schedule:
+  # 00:00 UTC every Saturday, don't bother anyone
+  - cron: '0 0 * * 6'
+
+jobs:
+
+  memleak_tests:
+    name: Build memory leak tests (${{ matrix.os }}, ${{ matrix.python_version }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-12]
+        python_version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13-dev"]
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
+
+      - uses: actions/setup-python@v5
+        name: Install Python
+        with:
+          python-version: ${{ matrix.python_version }}
+
+      - name: Install build test dependencies
+        run: pip install setuptools
+
+      - name: Install Yajl
+        if: ${{ matrix.os == 'ubuntu-latest' }}
+        run: sudo apt install libyajl-dev
+
+      - name: Build ijson
+        env:
+          IJSON_EMBED_YAJL: ${{ matrix.os != 'ubuntu-latest' && '1' || '0' }}
+        run: python setup.py develop
+
+      - name: Install test dependencies
+        run: pip install -r test-requirements.txt
+
+      - name: Run memory leak tests
+        run: pytest --memleaks-only -v