Fix swift segment

The regex for the swift segment matches too much. Here I simplified it
to match the first number as this is probably the "main" version number.

powerlevel9k.zsh-theme

@@ -1065,12 +1065,10 @@ prompt_pyenv() {
 
 # Swift version
 prompt_swift_version() {
-  local swift_version=($(swift --version 2>/dev/null))
+  # Get the first number as this is probably the "main" version number..
+  local swift_version=$(swift --version 2>/dev/null | grep -o -E "[0-9.]+" | head -n 1)
   [[ -z "${swift_version}" ]] && return
 
-  # Extract semantic version
-  swift_version=$(echo ${swift_version} | sed -e 's/[^0-9.]*\([0-9.]*\).*/\1/')
-
   "$1_prompt_segment" "$0" "$2" "magenta" "white" "${swift_version}" 'SWIFT_ICON'
 }