pyodide: Remove embedded get-pip

Extract get-pip change in a separate commit
cc @jm @romain

/reviewed-on !621

component/pyodide/buildout.cfg

@@ -60,6 +60,14 @@ repository = https://lab.nexedi.com/Daetalus/pyodide.git
 location = ${buildout:parts-directory}/${:_buildout_section_name_}
 branch = master
 
+[get-pip]
+recipe = slapos.recipe.build:download
+# version 19.2.3
+url = https://github.com/pypa/get-pip/raw/309a56c5fd94bd1134053a541cb4657a4e47e09d/${:filename}
+md5sum = 6f489c199cb5be8a4b84c6bd7ad6e051
+filename = get-pip.py
+mode = 0755
+
 [pyodide-script]
 recipe = slapos.recipe.build
 location = ${buildout:parts-directory}/${:_buildout_section_name_}
@@ -78,7 +86,7 @@ openssl_location = ${openssl:location}
 gcc_bin_dir = ${gcc-8.2:location}/bin
 python_bin_dir = ${python3.7:location}/bin
 md5sum = 47ec6a091e503349d948760dc03bed51
-pip_script = ${:_profile_base_location_}/get-pip.py
+pip_script = ${get-pip:target}
 script =
   import subprocess, os, shutil