CI: Don't test min pyarrow version with multiple python versions (#51272)

Author: mroeschke

.github/workflows/ubuntu.yml

@@ -29,7 +29,7 @@ jobs:
       matrix:
         env_file: [actions-38.yaml, actions-39.yaml, actions-310.yaml, actions-311.yaml]
         pattern: ["not single_cpu", "single_cpu"]
-        pyarrow_version: ["7", "8", "9", "10"]
+        pyarrow_version: ["8", "9", "10"]
         include:
           - name: "Downstream Compat"
             env_file: actions-38-downstream_compat.yaml
@@ -79,23 +79,17 @@ jobs:
             test_args: "-W error::DeprecationWarning -W error::FutureWarning"
             error_on_warnings: "0"
         exclude:
-          - env_file: actions-38.yaml
-            pyarrow_version: "7"
           - env_file: actions-38.yaml
             pyarrow_version: "8"
           - env_file: actions-38.yaml
             pyarrow_version: "9"
-          - env_file: actions-39.yaml
-            pyarrow_version: "7"
           - env_file: actions-39.yaml
             pyarrow_version: "8"
           - env_file: actions-39.yaml
             pyarrow_version: "9"
-          - env_file: actions-311.yaml
-            pyarrow_version: "7"
-          - env_file: actions-311.yaml
+          - env_file: actions-310.yaml
             pyarrow_version: "8"
-          - env_file: actions-311.yaml
+          - env_file: actions-310.yaml
             pyarrow_version: "9"
       fail-fast: false
     name: ${{ matrix.name || format('{0} pyarrow={1} {2}', matrix.env_file, matrix.pyarrow_version, matrix.pattern) }}