Maintain case when making a URI from a file, make drive letter lowercase on windows

src/uri.zig

@@ -24,7 +24,17 @@ pub fn fromPath(allocator: *std.mem.Allocator, path: []const u8) ![]const u8 {
             try buf.append('%');
             try std.fmt.format(out_stream, "{X}", .{char});
         } else {
-            try buf.append(std.ascii.toLower(char));
+            try buf.append(char);
+        }
+    }
+
+    // On windows, we need to lowercase the drive name.
+    if (std.builtin.os.tag == .windows) {
+        if (buf.items.len > prefix.len + 1 and
+            std.ascii.isAlpha(buf.items[prefix.len]) and
+            std.mem.startsWith(u8, buf.items[prefix.len + 1 ..], "%3A"))
+        {
+            buf.items[prefix.len] = std.ascii.toLower(buf.items[prefix.len]);
         }
     }