Exclude unsupported Airflow versions for Python 3.11 tests (#824)

After #821 was added, tests in the matrix like [this
one](https://github.com/astronomer/astronomer-cosmos/actions/runs/7717880587/job/21037953569)
for Airflow v2.3 and Python 3.11 are failing because the minimum Airflow
version supported for 3.11 is v2.5.

This PR excludes Airflow v2.3 and 2.4 from the testing matrix for 3.11.

.github/workflows/test.yml

@@ -42,6 +42,11 @@ jobs:
       matrix:
         python-version: ["3.8", "3.9", "3.10", "3.11"]
         airflow-version: ["2.3", "2.4", "2.5", "2.6", "2.7", "2.8"]
+        exclude:
+          - python-version: "3.11"
+            airflow-version: "2.3"
+          - python-version: "3.11"
+            airflow-version: "2.4"
     steps:
       - uses: actions/checkout@v3
         with:
@@ -81,6 +86,11 @@ jobs:
       matrix:
         python-version: ["3.8", "3.9", "3.10", "3.11"]
         airflow-version: ["2.3", "2.4", "2.5", "2.6", "2.7", "2.8"]
+        exclude:
+          - python-version: "3.11"
+            airflow-version: "2.3"
+          - python-version: "3.11"
+            airflow-version: "2.4"
     services:
       postgres:
         image: postgres