fish: functions: Use newer eza which is replacement of exa

fish/.config/fish/functions/l.fish

@@ -1,3 +1,3 @@
-function l -w exa
-    exa -l $argv
+function l -w eza
+    eza -l $argv
 end

fish/.config/fish/functions/ll.fish

@@ -1,3 +1,3 @@
-function ll -w exa
-    exa -la $argv
+function ll -w eza
+    eza -la $argv
 end

fish/.config/fish/functions/lt.fish

@@ -1,3 +1,3 @@
-function lt -w exa
-    exa --tree --git-ignore $argv
+function lt -w eza
+    eza --tree --git-ignore $argv
 end