component/depot_tools: fix typo on revision

as a result, this checkout was not pinned and software was not
reproducible

component/depot_tools/buildout.cfg

@@ -7,5 +7,5 @@ parts =
 [depot_tools]
 recipe = slapos.recipe.build:gitclone
 repository = https://chromium.googlesource.com/chromium/tools/depot_tools.git
-revsion = e023d4482012d89690f6a483e877eceb47c4501e
+revision = e023d4482012d89690f6a483e877eceb47c4501e
 git-executable = ${git:location}/bin/git

[Jérome Perrin]

@tomo @xavier_thompson FYI, the build error with chromium-headless were because of this.

It took me some time to figure this out, https://chromium.googlesource.com/chromium/tools/depot_tools.git#updating says that :

depot_tools updates itself automatically when running gclient tool. To disable auto update, set the environment variable DEPOT_TOOLS_UPDATE=0 or run ./update_depot_tools_toggle.py --disable.

but maybe we don't even need this, I'm trying to build locally and it does not seem to self update here