github: pin minimum libvalkey version for now

`pip install <pkg>` fails if the only available package version is a
beta. `libvalkey 3.0.0` is not suitable for the test and was yanked,
`libvalkey 4.0.0b1` is the most recent version. To use it, we need to
specify it explicitly. Provide it as a minimum version.

Signed-off-by: Mikhail Koviazin <[email protected]>

Author: Mikhail Koviazin

.github/workflows/integration.yaml

@@ -75,7 +75,7 @@ jobs:
            pip install -r requirements.txt
            pip install -r dev_requirements.txt
            if [ "${{matrix.connection-type}}" == "libvalkey" ]; then
-            pip install libvalkey
+            pip install "libvalkey>=4.0.0b1"
            fi
            invoke devenv
            sleep 10 # time to settle
@@ -123,7 +123,7 @@ jobs:
           pip install -r requirements.txt
           pip install -r dev_requirements.txt
           if [ "${{matrix.connection-type}}" == "libvalkey" ]; then
-            pip install libvalkey
+            pip install "libvalkey>=4.0.0b1"
           fi
           invoke devenv
           sleep 10 # time to settle