i18n: Correct text string

Signed-off-by: Valdnet <47037905+Valdnet@users.noreply.github.com>

app/src/main/res/values/strings.xml

@@ -335,7 +335,7 @@
     <string name="nc_guest_access">Guest access</string>
     <string name="nc_guest_access_allow_title">Allow guests</string>
     <string name="nc_guest_access_allow_summary">Allow guests to share a public link to join this conversation.</string>
-    <string name="nc_guest_access_allow_failed">Can\'t en-/disable guest access.</string>
+    <string name="nc_guest_access_allow_failed">Cannot enable/disable guest access.</string>
     <string name="nc_guest_access_password_title">Password protection</string>
     <string name="nc_guest_access_password_summary">Set a password to restrict who can use the public link.</string>
     <string name="nc_guest_access_password_dialog_title">Guest access password</string>