correct pip install; don't build 2.7 through 3.4

.github/workflows/ci.yaml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["2.7", "3.3", "3.4", "3.5", "3.6", "3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.5", "3.6", "3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
         allowed-to-fail: [false]
         include:
           - python-version: "3.13"
@@ -37,7 +37,8 @@ jobs:
       - name: Install dependencies
         continue-on-error: ${{ matrix.allowed-to-fail }}
         run: |
-          pip install -e .[dev]
+          pip install -r requirements.txt
+          pip install -e .
 
       - name: Run tests
         continue-on-error: ${{ matrix.allowed-to-fail }}