矩形输出而非方形输出

Question

它看起来是矩形的，但它应该是正方形的？知道为什么吗？

\documentclass[borders=2cm]{standalone}
 \usepackage{tikz,pgfplots} 
   \pgfplotsset{compat=newest}
\begin{document}
  \begin{tikzpicture}
\begin{axis}[
     xlabel={x},
     ylabel={y},
     axis lines=left,
    axis lines=middle,
    enlargelimits={abs=0.2},
    xmin = 0, xmax = 1.5,
    ymin = -1, ymax = 1.5,
    ytick={1},
    yticklabels={1},
    xtick= {1},
    xticklabels={1},                      
            ]
    \draw(0,1)--(1,1)--(1,0);

\end{axis}

    \end{tikzpicture}
\end{document}