🚑 Try surrounding conditional statement in quotes

Another try to see if it's possible to get around `Error: /home/runner/work/conda-lock-refresh/conda-lock-refresh/./action.yml: (Line: 55, Col: 38, Idx: 1521) - (Line: 55, Col: 38, Idx: 1521): Mapping values are not allowed in this context.
Error: System.ArgumentException: Unexpected type '' encountered while reading 'action manifest root'. The type 'MappingToken' was expected`

action.yml

@@ -52,7 +52,7 @@ runs:
         rm --force conda-lock.yml
         conda-lock lock $MAMBA --file ${{ inputs.file }} --kind ${{ inputs.kind }} --platform ${{ inputs.platform }}
       env:
-        MAMBA: ${{ fromJSON('{"false": "--no-mamba", "true": "--mamba"}')[inputs.mamba] }}
+        MAMBA: "${{ fromJSON('{"false": "--no-mamba", "true": "--mamba"}')[inputs.mamba] }}"
       shell: bash -l {0}
 
     # Print contents of lockfile