build(deps): Bootstrap and Bootswatch 5.3.8

Bootstrap SCSS, the JS bundle and the Bootswatch themes go from 5.3.3 to
5.3.8 (bug fixes only), and wvc-main.min.css is recompiled from zephyr.
Bootswatch now gives table text the body color, and Lux drops card and
modal header borders.

Tests compile every theme with the pinned libsass and check that the
shipped CSS is zephyr from these sources. The update and rollback steps
put back the two files a theme change rewrites, or git refuses to pull
over them.

dev/scss/bootswatch/morph/_bootswatch.scss

@@ -1,4 +1,4 @@
-// Morph 5.3.3
+// Morph 5.3.8
 // Bootswatch
 
 
@@ -341,6 +341,18 @@ $box-shadow-dark: 5px 5px 10px rgba(darken($dark, 50%), .2), -5px -5px 10px rgba
   }
 }
 
+// Tables
+
+.table-primary,
+.table-secondary,
+.table-success,
+.table-warning,
+.table-danger,
+.table-info,
+.table-light {
+  --#{$prefix}table-color: #{$body-color};
+}
+
 // Forms
 
 .input-group {

dev/scss/bootswatch/morph/_variables.scss

@@ -1,4 +1,4 @@
-// Morph 5.3.3
+// Morph 5.3.8
 // Bootswatch
 
 $theme: "morph" !default;
@@ -73,6 +73,10 @@ $headings-color:              $link-color !default;
 
 $text-muted:                  lighten($body-color, 15%) !default;
 
+// Tables
+
+$table-color:                 initial !default;
+
 // Buttons + Forms
 
 $input-btn-padding-y:         1rem !default;