Update to node 14, update dependencies

[mpcsh]

I've been noticing some npm warnings; this PR addresses them.

• node updated from v12 to v14 (latest is 14.16.1 as of now)
• Ran npm audit fix and npm update (these do not cross semver major boundaries)

Things that'd be nice to do:

• Address npm outdated output:

  ❯ npm outdated
  Package                 Current  Wanted  Latest  Location
  autoprefixer              9.8.6   9.8.6  10.2.5  selfdefined
  concurrently              5.3.0   5.3.0   6.0.2  selfdefined
  eslint                    6.8.0   6.8.0  7.25.0  selfdefined
  eslint-config-prettier   6.15.0  6.15.0   8.3.0  selfdefined
  husky                     4.3.8   4.3.8   6.0.0  selfdefined
  markdown-it-anchor        5.3.0   5.3.0   7.1.0  selfdefined
  markdownlint-cli         0.23.2  0.23.2  0.27.1  selfdefined
  prettier                 1.19.1  1.19.1   2.2.1  selfdefined

• Address warnings on npm run serve:

  [1] DEPRECATION WARNING: $hue: Passing a unit other than deg (120s) is deprecated.
  [1] 
  [1] To preserve current behavior: $hue / 1s
  [1] 
  [1] See https://sass-lang.com/d/color-units
  [1] 
  [1]   ╷
  [1] 7 │   dark-green: hsl(120s, 100%, 15%),
  [1]   │               ^^^^^^^^^^^^^^^^^^^^
  [1]   ╵
  [1]     assets/css/abstracts/_variables.scss 7:15  @import
  [1]     assets/css/base.scss 4:9                   root stylesheet
  [1] 
  [1] WARNING: You probably don't mean to use the color value red in interpolation here.
  [1] It may end up represented as red, which will likely produce invalid CSS.
  [1] Always quote color names when using them as strings or map keys (for example, "red").
  [1] If you really want to use the color value here, use '"" + $name'.
  [1] 
  [1]   ╷
  [1] 4 │     --clr-#{$name}: #{$value};
  [1]   │             ^^^^^
  [1]   ╵
  [1]     assets/css/base/_custom-properties.scss 4:13  raw-color-names()
  [1]     assets/css/base/_custom-properties.scss 51:3  @import
  [1]     assets/css/base.scss 12:9                     root stylesheet

  ⚠️ Note: this output is incomplete and abridged.

[tatianamac]

@mpcsh This looks awesome!

For the two "nice to haves", they sound good to me. What would you need from me to add these to this PR (or would you want to add these to this PR?)

[mpcsh]

I think the two nice-to-haves should probably be their own PRs. for npm outdated, major semver upgrades can introduce breaking changes, so we should probably open up a new branch and introduce them one at a time. for those CSS warnings, I think I'd need to pair on them. will DM 😁

[ovlb]

@mpcsh Could you also update the .nvmrc file in a future PR?

[mpcsh]

Oh, I think we should probably remove it for the same reason as with this file (i.e., we shouldn't commit tool versioning configs, that should be up to folks to manage as they see fit)