fix(tei2tex): update xsl template fot ptr type page-ref

replace used function from replace-beginning (functx) to replace (fn); add 'E' sigla before page reference

xslt/tei2tex.xsl

@@ -1322,8 +1322,8 @@
     </xsl:template>
 
     <xsl:template match="ptr[@type = 'page-ref']">
-        <xsl:variable name="target" select="replace-beginning(@target, '#', '')"/>
-        <xsl:text>\at[</xsl:text>
+        <xsl:variable name="target" select="replace(@target, '^.*?#', '')"/>
+        <xsl:text>E\at[</xsl:text>
             <xsl:value-of select="$target" />
         <xsl:text>]</xsl:text>
     </xsl:template>