Add kdeconnect cask back, using recent kdeconnect and livecheck

Effectively reverts b49b9bbc (cc @yurikoles)

Edit: here's the diff view to make it more obvious what I changed after adding back the cask, since the merge request diff is just the entire file.

URL stanzas are deprecated in favor of livecheck: https://github.com/Homebrew/homebrew-cask/pull/186501

This pins the current latest version of master and adds a livecheck stanza to make updating easier. In the future if this were upstreamed to homebrew-cask, I believe the BrewTestBot could automatically update the version + sha256 using this livecheck.

Update: tested it now that the new nightly has built; updating requires a bit of an incantation but is ultimately pretty straightforward, and could probably be automated if wanted (I believe BrewTestBot does something like this automatically in https://github.com/Homebrew/homebrew-cask which could be used if upstreamed there):

cask upgrade process

$ brew livecheck --cask kdeconnect
kdeconnect: 4345 ==> 4354

$ brew bump-cask-pr --write-only kdeconnect --version 4354
==> Downloading https://cdn.kde.org/ci-builds/network/kdeconnect-kde/master/macos-x86_64/kdeconnect-kde-master-4354-macos-clang-x86_64.dmg
Already downloaded: /Users/ianchamberlain/Library/Caches/Homebrew/downloads/282afb975d68f38ab03e63c87549376cef486c8264e421ededbbc30046e3fe83--kdeconnect-kde-master-4354-macos-clang-x86_64.dmg
==> Downloading https://cdn.kde.org/ci-builds/network/kdeconnect-kde/master/macos-arm64/kdeconnect-kde-master-4354-macos-clang-arm64.dmg
Already downloaded: /Users/ianchamberlain/Library/Caches/Homebrew/downloads/ea14ceda74e8db7d8c481f674f5f7620ef10b9225a09d868c32344bff8ea84dd--kdeconnect-kde-master-4354-macos-clang-arm64.dmg
==> replace /version\s+["']4345["']/m with "version \"4354\""
==> replace "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" with "fe16d98f89e39a7eafbb48595ebbd6cc25090ada46c400e0004f5e7315792402"
==> replace "55cb17589f89470f24f68aead2799fbca3a9709d3da8bc55af27081ee29751f6" with "5d82ecc3a6ee2eedd8f3b2870811f60b5e50c70413196c86ca58a637a72ea1f8"
==> Downloading https://cdn.kde.org/ci-builds/network/kdeconnect-kde/master/macos-arm64/kde
Already downloaded: /Users/ianchamberlain/Library/Caches/Homebrew/downloads/ea14ceda74e8db7d8c481f674f5f7620ef10b9225a09d868c32344bff8ea84dd--kdeconnect-kde-master-4354-macos-clang-arm64.dmg
==> Downloading and extracting artifacts
==> Downloading https://cdn.kde.org/ci-builds/network/kdeconnect-kde/master/macos-arm64/kde
Already downloaded: /Users/ianchamberlain/Library/Caches/Homebrew/downloads/ea14ceda74e8db7d8c481f674f5f7620ef10b9225a09d868c32344bff8ea84dd--kdeconnect-kde-master-4354-macos-clang-arm64.dmg

1 file inspected, no offenses detected
==> try to fork repository with GitHub API
==> git add /opt/homebrew/Library/Taps/kde-mac/homebrew-kde/Casks/kdeconnect.rb
==> git checkout --no-track -b bump-kdeconnect-4354 origin/
==> git commit --no-edit --verbose --message='kdeconnect 4354' -- /opt/homebrew/Library/Taps/kde-mac/homebrew-kde/Casks/kdeconnect.rb
==> git push --set-upstream FORK_URL bump-kdeconnect-4354:bump-kdeconnect-4354
==> git checkout --quiet -
==> create pull request with GitHub API (base branch: )
                                                                                                                                                                                     
$ git diff
diff --git a/Casks/kdeconnect.rb b/Casks/kdeconnect.rb
index e703bad..370d110 100644
--- a/Casks/kdeconnect.rb
+++ b/Casks/kdeconnect.rb
@@ -2,13 +2,13 @@
   arch arm: "arm64", intel: "x86_64"
 
   # TODO: eventually also handle release versions (e.g. release-24.08 etc.)?
   base_url = "https://cdn.kde.org/ci-builds/network/kdeconnect-kde/master/macos-#{arch}"
 
-  version "4345"
-  sha256 arm:   "55cb17589f89470f24f68aead2799fbca3a9709d3da8bc55af27081ee29751f6",
-         intel: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+  version "4354"
+  sha256 arm:   "5d82ecc3a6ee2eedd8f3b2870811f60b5e50c70413196c86ca58a637a72ea1f8",
+         intel: "fe16d98f89e39a7eafbb48595ebbd6cc25090ada46c400e0004f5e7315792402"
 
   url "#{base_url}/kdeconnect-kde-master-#{version}-macos-clang-#{arch}.dmg"
   name "KDE Connect"
   desc "Enabling communication between all your devices"
   homepage "https://kdeconnect.kde.org/"