deps: upgrade npm to 6.13.6

6.13.6 (2020-01-09)

DEPENDENCIES

• 6dba897a1 pacote@9.5.12:
  • d2f4176 fix(git): Do not drop uid/gid when executing in root-owned directory (@isaacs)

6.13.5 (2020-01-09)

BUG FIXES

• fd0a802ec #550 Fix cache location for npm ci (@zhenyavinogradov)
• 4b30f3cca #648 fix(version): using 'allow-same-version', git commit --allow-empty and git tag -f (@rhengles)

TESTING

• e16f68d30 test(ci): add failing cache config test (@ruyadorno)
• 3f009fbf2 #659 test: fix bin-overwriting test on Windows (@isaacs)
• 43ae0791f #601 ci: Allow builds to run even if one fails (@XhmikosR)
• 4a669bee4 #603 Remove the unused appveyor.yml (@XhmikosR)
• 9295046ac #600 ci: switch to actions/checkout@v2 (@XhmikosR)

DOCUMENTATION

• f2d770ac7 #569 fix netlify publish path config (@claudiahdz)
• 462cf0983 #627 update gatsby dependencies (@felixonmars)
• 6fb5dbb72 #532 docs: clarify usage of global prefix (@jgehrcke)