failed seralization on LanguageCodes

[Redhawk18]

Describe the bug

A clear and concise description of what the bug is.
The library fails to deal with serialization from string to enum variant.

A clear and concise description of what you expected to happen.
the library handles the case because en and En are both English.

Minimal Reproducible Examples (MRE)

---- tests::categories stdout ----
[src/tests.rs:14:5] "{}" = "{}"
[src/tests.rs:14:5] &response = Err(
    Serialization(
        Error("unknown variant `en`, expected one of `Aa`, `Ab`, `Ae`, `Af`, `Ak`, `Am`, `An`, `Ar`, `As`, `Av`, `Ay`, `Az`, `Ba`, `Be`, `Bg`, `Bh`, `Bi`, `Bm`, `Bn`, `Bo`, `Br`, `Bs`, `Ca`, `Ce`, `Ch`, `Co`, `Cr`, `Cs`, `Cu`, `Cv`, `Cy`, `Da`, `De`, `Dv`, `Dz`, `Ee`, `El`, `En`, `Eo`, `Es`, `Et`, `Eu`, `Fa`, `Ff`, `Fi`, `Fj`, `Fo`, `Fr`, `Fy`, `Ga`, `Gd`, `Gl`, `Gn`, `Gu`, `Gv`, `Ha`, `He`, `Hi`, `Ho`, `Hr`, `Ht`, `Hu`, `Hy`, `Hz`, `Ia`, `Id`, `Ie`, `Ig`, `Ii`, `Ik`, `Io`, `Is`, `It`, `Iu`, `Ja`, `Jv`, `Ka`, `Kg`, `Ki`, `Kj`, `Kk`, `Kl`, `Km`, `Kn`, `Ko`, `Kr`, `Ks`, `Ku`, `Kv`, `Kw`, `Ky`, `La`, `Lb`, `Lg`, `Li`, `Ln`, `Lo`, `Lt`, `Lu`, `Lv`, `Mg`, `Mh`, `Mi`, `Mk`, `Ml`, `Mn`, `Mr`, `Ms`, `Mt`, `My`, `Na`, `Nb`, `Nd`, `Ne`, `Ng`, `Nl`, `Nn`, `No`, `Nr`, `Nv`, `Ny`, `Oc`, `Oj`, `Om`, `Or`, `Os`, `Pa`, `Pi`, `Pl`, `Ps`, `Pt`, `Qu`, `Rm`, `Rn`, `Ro`, `Ru`, `Rw`, `Sa`, `Sc`, `Sd`, `Se`, `Sg`, `Si`, `Sk`, `Sl`, `Sm`, `Sn`, `So`, `Sq`, `Sr`, `Ss`, `St`, `Su`, `Sv`, `Sw`, `Ta`, `Te`, `Tg`, `Th`, `Ti`, `Tk`, `Tl`, `Tn`, `To`, `Tr`, `Ts`, `Tt`, `Tw`, `Ty`, `Ug`, `Uk`, `Ur`, `Uz`, `Ve`, `Vi`, `Vo`, `Wa`, `Wo`, `Xh`, `Yi`, `Yo`, `Za`, `Zh`, `Zu`", line: 2, column: 16),
    ),
)

thread 'tests::categories' panicked at src/tests.rs:15:5: