This is a hack that you can use until you get a better solution. Specify the tick labels yourself:
using Plots
pyplot()
x = 1:10
y = rand(10)
plot(x, y,
guidefontsize = 12, tickfontsize = 10,
xtick = (2:2:10, ["2", "4", "6", "8", "10"]),
ytick = (0.2:0.2:1, ["0.2", "0.4", "0.6", "0.8", "1.0"]),
xlabel = "x",
ylabel = "y",
fontfamily = "Times New Roman")