fixup

Author: rnro

.github/workflows/unit_tests.yml

@@ -84,6 +84,7 @@ jobs:
         env:
           SWIFT_VERSION: ${{ matrix.swift.swift_version }}
           COMMAND: "swift test"
+          COMMAND_OVERRIDE_5_9: ""
           COMMAND_OVERRIDE_5_10: "swift test ${{ inputs.linux_5_10_arguments_override }}"
           COMMAND_OVERRIDE_6_0: "swift test ${{ inputs.linux_6_0_arguments_override }}"
           COMMAND_OVERRIDE_6_1: "swift test ${{ inputs.linux_6_1_arguments_override }}"