use value instead of size

Author: nilchia

tools/flexynesis/flexynesis.xml

@@ -580,7 +580,7 @@
             </output_collection>
             <output name="model" ftype="safetensors">
                 <assert_contents>
-                    <has_size size="107104"/>
+                    <has_size value="107104"/>
                 </assert_contents>
             </output>
         </test>
@@ -766,7 +766,7 @@
             </output_collection>
             <output name="model" ftype="safetensors">
                 <assert_contents>
-                    <has_size size="198076"/>
+                    <has_size value="198076"/>
                 </assert_contents>
             </output>
         </test>
@@ -826,7 +826,7 @@
             </output_collection>
             <output name="model" ftype="safetensors">
                 <assert_contents>
-                    <has_size size="194476"/>
+                    <has_size value="194476"/>
                 </assert_contents>
             </output>
         </test>