Adding GH actions exercise solutions

.github/workflows/exercise1.yml

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+---
+name: Exercise1
+on: 
+  - push
+
+jobs:
+  exercise1:
+    runs-on: "ubuntu-24.04"
+    steps:
+      - run: echo "hello"
+

.github/workflows/exercise2.yml

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+---
+name: Exercise2
+on: 
+  - push
+
+jobs:
+  exercise2:
+    runs-on: "ubuntu-24.04"
+
+    steps:
+      # Checkout this repository
+      - uses: actions/checkout@v4
+
+      # Setup the specified Python version
+      - name: "Set up Python 3.12"
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - run: echo "hello"
+
+      - run: python --version
+

.github/workflows/exercise3.yml

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+---
+name: Exercise3
+on: 
+  - push
+
+jobs:
+  exercise3:
+
+    strategy:
+      matrix:
+        python-version: ["3.10", "3.11", "3.12"]
+        platform: ["ubuntu-24.04"]
+    runs-on: ${{ matrix.platform }}
+
+    steps:
+      # Checkout this repository
+      - uses: actions/checkout@v4
+
+      # Setup the specified Python version
+      - name: "Set up Python ${{ matrix.python-version }}"
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - run: echo "hello"
+
+      - run: python --version
+

.github/workflows/exercise4.yml

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+---
+name: Exercise4
+on: 
+  - push
+
+jobs:
+  exercise4:
+
+    strategy:
+      matrix:
+        python-version: ["3.10", "3.11", "3.12"]
+        platform: ["ubuntu-24.04", "windows-2022"]
+    runs-on: ${{ matrix.platform }}
+
+    steps:
+      # Checkout this repository
+      - uses: actions/checkout@v4
+
+      # Setup the specified Python version
+      - name: "Set up Python ${{ matrix.python-version }}"
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - run: echo "hello"
+
+      - run: python --version
+