EnvWizard does not work correctly when the environment variable name contains numbers.

[rexzhang]

CC_TEST=cc_test_new
CC_2TEST=cc_2test_new

class EnvVarAbc(EnvWizard):
    ABC: str

class EnvVar(EnvVarAbc):
    class _(EnvWizard.Meta):
        env_file = True

    CC_TEST: str = "cc_test"
    CC_2TEST: str = "cc_2test"

EV = EnvVar()

the value of EV.CC_TEST is the expected cc_test_new.
but, The value of EV.CC_2TEST is not the expected cc_2test_new, it is cc_2test