Update .gitlab-ci.yml file

.gitlab-ci.yml

@@ -19,7 +19,6 @@ before_script:
   # Install test dependencies
   - pip install -r requirements_test.txt
   - export PYTEST_QT_API=$QT_API
-  - export MPLBACKEND=qtagg
 
 .run-test:
   stage: test
@@ -50,7 +49,7 @@ run-test-3.10-pyqt5:
 
 run-test-3.10-pyqt6:
   variables:
-    QT_API: PyQt6
+    QT_API: pyqt6
   image: python:3.10
   extends: ".run-test"
 
@@ -70,7 +69,7 @@ run-test-3.11-pyqt5:
 
 run-test-3.11-pyqt6:
   variables:
-    QT_API: PyQt6
+    QT_API: pyqt6
   image: python:3.11
   extends: ".run-test"
 
@@ -82,13 +81,13 @@ run-test-3.12-pyqt5:
 
 run-test-3.12-pyqt6:
   variables:
-    QT_API: PyQt6
+    QT_API: pyqt6
   image: python:3.12
   extends: ".run-test"
 
 run-test-3.13-pyqt6:
   variables:
-    QT_API: PyQt6
+    QT_API: pyqt6
   image: python:3.13
   extends: ".run-test"