Use different icons

aleksis/apps/chronos/frontend/components/substitutions/SubstitutionCard.vue

@@ -44,7 +44,7 @@ import createOrPatchMixin from "aleksis.core/mixins/createOrPatchMixin.js";
             color="error"
             class="mb-2"
           >
-            <v-icon left> $cancel </v-icon>
+            <v-icon left>mdi-account-off-outline</v-icon>
             <div class="text-decoration-line-through">
               {{ teacher.fullName }}
             </div>
@@ -61,7 +61,7 @@ import createOrPatchMixin from "aleksis.core/mixins/createOrPatchMixin.js";
             @click:close="removeTeacher(data.item)"
           >
             <v-icon left v-if="getTeacherStatus(data.item) === 'new'">
-              mdi-plus
+              mdi-account-plus-outline
             </v-icon>
             {{ data.item.fullName }}
           </v-chip>