Add github action

.github/workflows/ci.yml

@@ -0,0 +1,42 @@
+name: Build Qwt
+
+on: [push, pull_request]
+jobs:
+  ResInsight-x64:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+        qtver: [5.12.12, 6.5.3]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Qt
+        uses: jurplel/install-qt-action@v3
+        with:
+          version: ${{ matrix.qtver }}
+          dir: "${{ github.workspace }}/Qt/"
+          cache: true
+          cache-key-prefix: ${{ matrix.qtver }}-${{ matrix.os }}
+
+      - name: Install Linux dependencies
+        if: "contains( matrix.os, 'ubuntu')"
+        run: sudo apt-get install libxkbcommon-x11-0 libgl1-mesa-dev mesa-common-dev libglfw3-dev libglu1-mesa-dev
+
+      - name: Use MSVC (Windows)
+        uses: ilammy/msvc-dev-cmd@v1
+
+      - name: Configure 5.12
+        if: "contains( matrix.qtver, '5.12')"
+        run: |
+          cmake -S . -B build
+
+      - name: Configure 6.5
+        if: "contains( matrix.qtver, '6.5')"
+        run: |
+          cmake -S . -DUSE_QT6=TRUE -B build
+  
+      - name: Build
+        run: cmake --build build