Fix framicon size for non-square icons

beamerinnerthemetuhh.sty

@@ -9,7 +9,7 @@
     \begin{tikzpicture}
       \begin{beamercolorbox}{tuhh teal}
         \useasboundingbox (0,0) rectangle(\the\paperwidth,\the\paperheight);
-        \node[outer sep=0, inner sep=0, anchor=center] (tuhh_logo) at (\the\paperwidth-5.34mm-16.05mm, \the\paperheight-16.05mm-12.91mm) {\includegraphics[width=25.82mm]{\frameicon}};
+        \node[outer sep=0, inner sep=0, anchor=center] (tuhh_logo) at (\the\paperwidth-5.34mm-16.05mm, \the\paperheight-16.05mm-12.91mm) {\includegraphics[width=25.82mm, height=25.82mm, keepaspectratio]{\frameicon}};
         \useasboundingbox (0,0) rectangle(\the\paperwidth,\the\paperheight);
         %date
         \node[rectangle,
@@ -82,7 +82,7 @@
         \useasboundingbox (0,0) rectangle(\the\paperwidth,\the\paperheight);
         \node[outer sep=0, inner sep=0] (tuhh_logo) at (5.29mm+29.755mm, \the\paperheight-122.41mm-25.815mm) {\includegraphics[width=59.51mm]{.theme_imgs/TUHH_agenda_icon.pdf}};
         \useasboundingbox (0,0) rectangle(\the\paperwidth,\the\paperheight);
-        \node[outer sep=0, inner sep=0, anchor=center] (tuhh_logo) at (\the\paperwidth-5.34mm-16.05mm, \the\paperheight-16.05mm-12.91mm) {\includegraphics[width=25.82mm]{\frameicon}};
+        \node[outer sep=0, inner sep=0, anchor=center] (tuhh_logo) at (\the\paperwidth-5.34mm-16.05mm, \the\paperheight-16.05mm-12.91mm) {\includegraphics[width=25.82mm, height=25.82mm, keepaspectratio ]{\frameicon}};
         \useasboundingbox (0,0) rectangle(\the\paperwidth,\the\paperheight);
         %date
         \node[rectangle,