Fix typo

Author: ianayl

devops/actions/benchmarking/aggregate/action.yml

@@ -26,7 +26,7 @@ runs:
     shell: bash
     run: |
       # DO NOT use inputs.lookback_days directly, only use SANITIZED_TIMESTAMP.
-      SANITIZED_LOOKBACK_DAYS ="$(echo '${{ inputs.lookback_days }}' | grep -o "^[0-9]$")"
+      SANITIZED_LOOKBACK_DAYS="$(echo '${{ inputs.lookback_days }}' | grep -o "^[0-9]$")"
       if [ -z "$SANITIZED_TIMESTAMP" ]; then
         echo "Please ensure inputs.lookback_days is a number.
         exit 1