Remove gspell

7e7dcedaf ported from GTK3 to GTK4.
It also removed gspell from main/CMakeLists.txt.

I assume that gspell is not needed anymore and we can thus remove the
requirement from the CI and the cmake file as well.

.github/workflows/build.yml

@@ -7,7 +7,7 @@ jobs:
       - uses: actions/checkout@v2
       - run: sudo apt-get update
       - run: sudo apt-get remove libunwind-14-dev
-      - run: sudo apt-get install -y build-essential gettext cmake valac libgee-0.8-dev libsqlite3-dev libgtk-4-dev libnotify-dev libgpgme-dev libsoup2.4-dev libgcrypt20-dev libqrencode-dev libgspell-1-dev libnice-dev libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev libsrtp2-dev libwebrtc-audio-processing-dev libadwaita-1-dev
+      - run: sudo apt-get install -y build-essential gettext cmake valac libgee-0.8-dev libsqlite3-dev libgtk-4-dev libnotify-dev libgpgme-dev libsoup2.4-dev libgcrypt20-dev libqrencode-dev libnice-dev libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev libsrtp2-dev libwebrtc-audio-processing-dev libadwaita-1-dev
       - run: ./configure --with-tests --with-libsignal-in-tree
       - run: make
       - run: build/xmpp-vala-test

cmake/FindGspell.cmake

@@ -1,14 +0,0 @@
-include(PkgConfigWithFallback)
-find_pkg_config_with_fallback(Gspell
-    PKG_CONFIG_NAME gspell-1
-    LIB_NAMES gspell-1
-    INCLUDE_NAMES gspell.h
-    INCLUDE_DIR_SUFFIXES gspell-1 gspell-1/gspell
-    DEPENDS GTK3
-)
-
-include(FindPackageHandleStandardArgs)
-find_package_handle_standard_args(Gspell
-    REQUIRED_VARS Gspell_LIBRARY
-    VERSION_VAR Gspell_VERSION)
-