typo fix

Author: jeremymanning

data/people.xlsx

@@ -170,7 +170,7 @@ <h3>ellie mattox | undergrad</h3>
 
             <div class="people-grid">
                 <div class="person-card">
-                    <img src="images/people/evan_mcdermid" alt="evan mcdermid">
+                    <img src="images/people/evan_mcdermid.png" alt="evan mcdermid">
                     <h3>evan mcdermid | undergrad</h3>
                     <p>Evan is a Mathematics major and Computer Science minor. He is interested in algorithmic trading, algorithmic problem solving, and building models of financial market dynamics.</p>
                 </div>