CWL steps given in alphabetical order rather than the order in the CWL file

If I load a CWL workflow using `load_document_by_uri` then the object .steps are in alphabetical order rather than the order they were given in the file.

For example parsing the attached file

``` python
cwl_obj = load_document_by_uri(cwl_filename)
for step in cwl_obj.steps:
print( step.id.split("#")[-1])
```

will output
`'ProteinProphet_02', 'StPeter_04', 'XTandem_01', 'XTandem_03'`
instead of
`'XTandem_01', 'ProteinProphet_02', 'XTandem_03', 'StPeter_04'`

File contents:
``` yaml

# WorkflowNo_22
# This workflow is generated by APE (https://github.com/sanctuuary/APE).
cwlVersion: v1.2
class: Workflow

label: WorkflowNo_22
doc: A workflow including the tool(s) XTandem, ProteinProphet, XTandem, StPeter.

inputs:
input_1:
type: File
format: "http://edamontology.org/format_3244" # mzML
input_2:
type: File
format: "http://edamontology.org/format_1929" # FASTA
steps:
XTandem_01:
run: https://raw.githubusercontent.com/Workflomics/tools-and-domains/main/cwl-tools/xtandem/xtandem.cwl
in:
XTandem_in_1: input_1
XTandem_in_2: input_2
out: [XTandem_out_1]
ProteinProphet_02:
run: https://raw.githubusercontent.com/Workflomics/tools-and-domains/main/cwl-tools/proteinprophet/proteinprophet.cwl
in:
ProteinProphet_in_1: XTandem_01/XTandem_out_1
ProteinProphet_in_2: input_2
out: [ProteinProphet_out_1, ProteinProphet_out_2]
XTandem_03:
run: https://raw.githubusercontent.com/Workflomics/tools-and-domains/main/cwl-tools/xtandem/xtandem.cwl
in:
XTandem_in_1: input_1
XTandem_in_2: input_2
out: [XTandem_out_1]
StPeter_04:
run: https://raw.githubusercontent.com/Workflomics/tools-and-domains/main/cwl-tools/stpeter/stpeter.cwl
in:
StPeter_in_1: ProteinProphet_02/ProteinProphet_out_1
StPeter_in_2: XTandem_03/XTandem_out_1
StPeter_in_3: input_1
out: [StPeter_out_1]
outputs:
output_1:
type: File
format: "http://edamontology.org/format_3747" # protXML
outputSource: StPeter_04/StPeter_out_1

```

Start by reproducing the issue with the supplied CWL workflow and tracing load_document_by_uri while it builds cwl_obj.steps. Compare the resulting step sequence with the order in the file; done when the object preserves that source order rather than alphabetical order.

Written by the indexing model from the issue text.