SCons: Format buildsystem files with psf/black

Configured for a max line length of 120 characters.

psf/black is very opinionated and purposely doesn't leave much room for
configuration. The output is mostly OK so that should be fine for us,
but some things worth noting:

- Manually wrapped strings will be reflowed, so by using a line length
  of 120 for the sake of preserving readability for our long command
  calls, it also means that some manually wrapped strings are back on
  the same line and should be manually merged again.

- Code generators using string concatenation extensively look awful,
  since black puts each operand on a single line. We need to refactor
  these generators to use more pythonic string formatting, for which
  many options are available (`%`, `format` or f-strings).

- CI checks and a pre-commit hook will be added to ensure that future
  buildsystem changes are well-formatted.

2 files changed, 5 insertions, 4 deletions

diff --git a/modules/mbedtls/SCsub b/modules/mbedtls/SCsub
index 0c6c703e16..5f5d25a3ee 100755
--- a/modules/mbedtls/SCsub
+++ b/modules/mbedtls/SCsub
@@ -1,11 +1,11 @@
 #!/usr/bin/env python
 
-Import('env')
-Import('env_modules')
+Import("env")
+Import("env_modules")
 
 env_mbed_tls = env_modules.Clone()
 
-if env['builtin_mbedtls']:
+if env["builtin_mbedtls"]:
     # Thirdparty source files
     thirdparty_sources = [
         "aes.c",
@@ -86,7 +86,7 @@ if env['builtin_mbedtls']:
         "x509_csr.c",
         "x509write_crt.c",
         "x509write_csr.c",
-        "xtea.c"
+        "xtea.c",
     ]
 
     thirdparty_dir = "#thirdparty/mbedtls/library/"
diff --git a/modules/mbedtls/config.py b/modules/mbedtls/config.py
index 1c8cd12a2d..d22f9454ed 100755
--- a/modules/mbedtls/config.py
+++ b/modules/mbedtls/config.py
@@ -1,5 +1,6 @@
 def can_build(env, platform):
     return True
 
+
 def configure(env):
     pass