Fix reference Spehr -> Spoehr

[xrotwang]

glottolog/glottolog#1147

@book{spehr:54,
    author = {Spoehr, Alexander},
    title = {Saipan: The Ethnology of a War-Devastated Island},
    journal = {Fieldiana: Anthropology},
    volume = {41},
    address={Chicago},
    publisher ={Chicago Natural History Museum},
    pages = {1-383},
    year = {1954},
    url = {https://libsysdigi.library.uiuc.edu/OCA/Books2008-11/saipanethnologyo41spoe/saipanethnologyo41spoe.pdf},
    citekeys = {cldf5:spehr1954},
    glottolog_ref_id = {686625},
    hhtype = {ethnographic},
    isreferencedby = {cldf5},
    key = {Spehr (1954)},
    lgcode = {[caro1242]}
}