Fix `browse-url-default-scheme` custom :type

* lisp/net/browse-url.el (browse-url-default-scheme): Fix custom
:type.
10 jobs for master in 59 minutes and 35 seconds (queued for 6 seconds)
Status Job ID Name Coverage
  Build Images
failed #76101
build-image-inotify

00:02:01

 
  Normal
skipped #76102
test-all-inotify
 
  Platform Images
passed #76103
build-image-eglot

00:57:33

failed #76105
build-image-gnustep

00:01:57

passed #76104
build-image-tree-sitter

00:58:16

 
  Platforms
passed #76106
test-eglot

00:01:43

skipped #76108
test-gnustep
passed #76107
test-tree-sitter

00:00:58

 
  Native Comp Images
failed #76109
build-native-comp-speed2

00:01:55

 
  Native Comp
skipped #76110
test-native-comp-speed2
 
Name Stage Failure
failed
build-native-comp-speed2 Native Comp Images
 > [internal] load build context:
------
rpc error: code = Unavailable desc = transport is closing
Running after script...
$ test -n "$(docker ps -aq -f name=${test_name})" && docker cp ${test_name}:checkout/test ${test_name}
$ test -n "$(docker ps -aq -f name=${test_name})" && docker rm ${test_name}
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
find: build-native-comp-speed2-194a8f5c: No such file or directory
ERROR: Job failed: exit code 1
failed
build-image-inotify Build Images
context canceled
Running after_script
Running after script...
$ test -n "$(docker ps -aq -f name=${test_name})" && docker cp ${test_name}:checkout/test ${test_name}
$ test -n "$(docker ps -aq -f name=${test_name})" && docker rm ${test_name}
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
find: build-image-inotify-194a8f5c: No such file or directory
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1

failed
build-image-gnustep Platform Images
rpc error: code = Unavailable desc = transport is closing
Running after_script
Running after script...
$ test -n "$(docker ps -aq -f name=${test_name})" && docker cp ${test_name}:checkout/test ${test_name}
$ test -n "$(docker ps -aq -f name=${test_name})" && docker rm ${test_name}
find: build-image-gnustep-194a8f5c: No such file or directory
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1