fix: remove duplicated `ui.help` in themes

the bottom value is used, so i've removed the top `ui.help` values from all themes

also, the values are not merged, so:

```toml
"ui.help" = { modifiers = ["reversed"] }
"ui.help" = { fg = "white", bg = "black" }
```

is equal to:

```toml
"ui.help" = { fg = "white", bg = "black" }
```

base16_theme.toml

@@ -10,7 +10,6 @@
 "comment" = { fg = "gray" }
 "ui.statusline" = { fg = "black", bg = "white" }
 "ui.statusline.inactive" = { fg = "gray", bg = "white" }
-"ui.help" = { modifiers = ["reversed"] }
 "ui.cursor" = { fg = "white", modifiers = ["reversed"] }
 "variable" = "red"
 "constant.numeric" = "yellow"

runtime/themes/autumn.toml

@@ -17,7 +17,6 @@
 "ui.selection" = { bg = "my_gray3" }
 "comment" = { fg = "my_gray4", modifiers = ["italic"] }
 "ui.statusline" = { fg = "my_gray5", bg = "my_gray2" }
-"ui.help" = { fg = "my_gray5", bg = "my_gray2" }
 "ui.cursor" = { fg = "my_gray5", modifiers = ["reversed"] }
 "ui.cursor.primary" = { fg = "my_white", modifiers = ["reversed"] }
 "ui.text" = "my_white"

runtime/themes/base16_default_dark.toml

@@ -11,7 +11,6 @@
 "ui.selection" = { bg = "base02" }
 "comment" = { fg = "base03", modifiers = ["italic"] }
 "ui.statusline" = { fg = "base04", bg = "base01" }
-"ui.help" = { fg = "base04", bg = "base01" }
 "ui.cursor" = { fg = "base04", modifiers = ["reversed"] }
 "ui.cursor.primary" = { fg = "base05", modifiers = ["reversed"] }
 "ui.text" = "base05"

runtime/themes/base16_default_light.toml

@@ -10,7 +10,6 @@
 "ui.selection" = { bg = "base02" }
 "comment" = { fg = "base03", modifiers = ["italic"] }
 "ui.statusline" = { fg = "base04", bg = "base01" }
-"ui.help" = { fg = "base04", bg = "base01" }
 "ui.cursor" = { fg = "base04", modifiers = ["reversed"] }
 "ui.cursor.primary" = { fg = "base05", modifiers = ["reversed"] }
 "ui.virtual" = "base03"

runtime/themes/rose_pine.toml

@@ -10,7 +10,6 @@
 "comment" = "subtle"
 "ui.statusline" = {fg = "foam", bg = "surface" }
 "ui.statusline.inactive" = { fg = "iris", bg = "surface" }
-"ui.help" = { fg = "foam", bg = "surface" }
 "ui.cursor" = { fg = "rose", modifiers = ["reversed"] }
 "ui.text" = { fg = "text" }
 "ui.text.focus" = { fg = "foam", modifiers = ["bold"]}

runtime/themes/rose_pine_dawn.toml

@@ -10,7 +10,6 @@
 "comment" = "subtle"
 "ui.statusline" = {fg = "foam", bg = "surface" }
 "ui.statusline.inactive" = { fg = "iris", bg = "surface" }
-"ui.help" = { fg = "foam", bg = "surface" }
 "ui.cursor" = { fg = "rose", modifiers = ["reversed"] }
 "ui.text" = { fg = "text" }
 "ui.text.focus" = { fg = "foam", modifiers = ["bold"]}