fix: unreachable case statement due to uppercase strings in receipe parser

[rkost]

We are using lower() in the match line, thus we cannot have uppercase strings in the case statements.

This bug broke the example recipe located at src/pypts/examples/environment_setup_tools/Package_based_setup/Package_based_recipe.yml:

DEBUG : pypts.recipe : File loader returned recipe_data type: <class 'generator'>
DEBUG : pypts.recipe : Recipe main data keys: dict_keys(['name', 'version', 'recipe_version', 'description', 'main_sequence', 'test_package', 'globals'])
DEBUG : pypts.recipe : Processing sequence 1: main
ERROR : pypts.recipe : Failed to create sequence 'main': name 'sshconnectstep' is not defined
ERROR : pypts.recipe : Failed to load recipe from /home/rkost/repos/cern/pts-framework/src/pypts/examples/environment_setup_tools/Package_based_setup/Package_based_recipe.yml: name 'sshconnectstep' is not defined
Traceback (most recent call last):
  File "/home/rkost/repos/cern/pts-framework/src/pypts/recipe.py", line 427, in __load_recipe
    self.sequences[sequence["sequence_name"]] = Sequence(sequence_data=sequence)
                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/rkost/repos/cern/pts-framework/src/pypts/recipe.py", line 570, in __init__
    self.steps.append(Step.build_step(step_data))
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/rkost/repos/cern/pts-framework/src/pypts/recipe.py", line 837, in build_step
    new_step: Step = eval(step_type + "(**step_data)")
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<string>", line 1, in <module>
NameError: name 'sshconnectstep' is not defined. Did you mean: 'SSHConnectStep'?