Now that italics are working again, revisit theme

Add back italics.  They don't work in TMUX still, but at least I can now
use them in the theme to better hilight function parameters.

config/helix/themes/glfmn.toml

@@ -7,17 +7,14 @@ inherits = "gruvbox"
 # Make operators less loud but stil stand out
 "operator" = "fg3"
 
-# Remove italics (can cause issues with tmux)
-"comment" = "gray1"
-
 # Unify look of variables with slight contrast difference to emphasize
 # function parameters.
 "variable" = "fg2"
-"variable.parameter" = "fg1"
-"variable.builtin" = "fg1"
+"variable.parameter" = { fg = "fg1", modifiers = ["italic"] }
+"variable.builtin" = { fg = "fg1", modifiers = ["italic"] }
 
 # Unify look of functions
-"function" = "green1" 
+"function" = "green1"
 "function.macro" = "aqua1"
 "function.builtin" = { fg = "green1", modifiers = ["bold"] }