template: augmente le contraste du texte pour une meilleure accessibilité

Related to #11

app/templates/base.html

@@ -23,12 +23,12 @@
       <div class="container">
         <div class="row">
           <div class="col-6">
-            <div class="d-sm-inline p-2 small"><a href="https://git.laquadrature.net/la-quadrature-du-net/Attrap_front">Code source</a></div>
-            <div class="d-sm-inline p-2 small"><a href="/mentions-legales">Mentions légales</a></div>
+            <div class="d-sm-inline p-2 small"><a href="https://git.laquadrature.net/la-quadrature-du-net/Attrap_front" class="text-primary-emphasis">Code source</a></div>
+            <div class="d-sm-inline p-2 small"><a href="/mentions-legales" class="text-primary-emphasis">Mentions légales</a></div>
           </div>
           <div class="col-6 text-end">
-            <div class="d-sm-inline p-2 small">Un outil de <a href="https://www.laquadrature.net" class="non-breakable-inline">La Quadrature du Net</a></div>
-            <div class="d-sm-inline p-2 small"><a href="https://www.laquadrature.net/donner">Faire un don</a></div>
+            <div class="d-sm-inline p-2 small">Un outil de <a href="https://www.laquadrature.net" class="non-breakable-inline text-primary-emphasis">La Quadrature du Net</a></div>
+            <div class="d-sm-inline p-2 small"><a href="https://www.laquadrature.net/donner" class="text-primary-emphasis">Faire un don</a></div>
           </div>
         </div>
       </div>