Correct invalid table markup

- Add required <tr> within <thead>
  - Add implicit <tbody> after <thead>

app/views/admin/events/index.html.haml

@@ -58,44 +58,46 @@
     .margin-event-table
       %table.datatable
         %thead
-          %th
-            %b ID
-          %th
-            %b Title
-          - if @program.rating_enabled?
+          %tr
             %th
-              %b Rating
-          %th
-            %b Submitter
-          %th
-            %b Speakers
-          - if @program.languages.present?
+              %b ID
             %th
-              %b Language
-          %th
-            %b Requires Registration
-          %th
-            %b Highlight
-          %th
-            %b Type
-          %th
-            %b Track
-          %th
-            %b Difficulty
-          %th
-            %b State
-          %th
-            .fa-solid.fa-comment
-          %th Add Survey
-        - @events.each do |event|
-          = render 'datatable_row',
-            event: event,
-            conference_id: @conference.short_title,
-            program: @program,
-            rating_enabled: @program.rating_enabled?,
-            show_votes: @program.show_voting?,
-            max_rating: @program.rating,
-            event_types: @event_types,
-            tracks: @tracks,
-            difficulty_levels: @difficulty_levels,
-            email_settings: @conference.email_settings
+              %b Title
+            - if @program.rating_enabled?
+              %th
+                %b Rating
+            %th
+              %b Submitter
+            %th
+              %b Speakers
+            - if @program.languages.present?
+              %th
+                %b Language
+            %th
+              %b Requires Registration
+            %th
+              %b Highlight
+            %th
+              %b Type
+            %th
+              %b Track
+            %th
+              %b Difficulty
+            %th
+              %b State
+            %th
+              .fa-solid.fa-comment
+            %th Add Survey
+        %tbody
+          - @events.each do |event|
+            = render 'datatable_row',
+              event: event,
+              conference_id: @conference.short_title,
+              program: @program,
+              rating_enabled: @program.rating_enabled?,
+              show_votes: @program.show_voting?,
+              max_rating: @program.rating,
+              event_types: @event_types,
+              tracks: @tracks,
+              difficulty_levels: @difficulty_levels,
+              email_settings: @conference.email_settings

app/views/admin/events/registrations.html.haml

@@ -18,12 +18,13 @@
     .well
       %table.datatable#registrations
         %thead
-          %th
-          %th Name
-          %th Email
-          %th Created At
-          %th Attended
-          %th Attended Conference
+          %tr
+            %th
+            %th Name
+            %th Email
+            %th Created At
+            %th Attended
+            %th Attended Conference
         %tbody
           - @event_registrations.each.with_index(1) do |event_registration, index|
             %tr

app/views/admin/events/show.html.haml

@@ -20,9 +20,10 @@
       .col-md-12
         %table.datatable
           %thead
-            %th ID
-            %th Description
-            %th Actions
+            %tr
+              %th ID
+              %th Description
+              %th Actions
           %tbody
             - @versions.each do |version|
               %tr