RRC: gitlab: Use Python 3 in virtualenv

This is a test to see if it removes the error here:

https://gitlab.denx.de/u-boot/custodians/u-boot-dm/-/jobs/24304

Signed-off-by: Simon Glass <sjg@chromium.org>
31 jobs for py3-working in 133 minutes and 27 seconds (queued for 533 minutes and 18 seconds)
Status Job ID Name Coverage
  Testsuites
passed #25466
all
Build envtools

00:00:25

passed #25465
all
Build tools-only

00:00:27

passed #25464
all
Check for configs without MAINTAINERS entry

00:00:23

passed #25467
all
Run binman, buildman, dtoc and patman testsuites

00:01:03

passed #25461
all
cppcheck

00:07:37

passed #25462
all
grep TODO/FIXME/HACK

00:00:34

passed #25463
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sloccount

00:00:44

 
  Test.Py
passed #25470
all
evb-ast2500 test.py

00:00:55

passed #25474
all
integratorcp_cm926ejs test.py

00:00:50

passed #25481
all
qemu-ppce500 test.py

00:00:50

passed #25482
all
qemu-riscv64 test.py

00:01:08

passed #25483
all
qemu-x86 test.py

00:01:29

passed #25484
all
qemu-x86_64 test.py

00:01:25

passed #25475
all
qemu_arm test.py

00:01:19

passed #25476
all
qemu_arm64 test.py

00:01:20

passed #25477
all
qemu_mips test.py

00:00:50

passed #25479
all
qemu_mips64 test.py

00:00:49

passed #25480
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qemu_mips64el test.py

00:00:49

passed #25478
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qemu_mipsel test.py

00:00:48

passed #25468
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sandbox test.py

00:03:16

passed #25471
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sandbox_flattree test.py

00:01:05

passed #25469
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sandbox_spl test.py

00:01:03

passed #25472
all
vexpress_ca15_tc2 test.py

00:00:51

passed #25473
all
vexpress_ca9x4 test.py

00:00:51

passed #25486
all
xilinx_versal_virt test.py

00:00:52

passed #25487
all
xtfpga test.py

00:00:49

passed #25485
all
zynq_zc702 test.py

00:00:53

 
  World Build
passed #25488
all
build all 32bit ARM platforms

00:51:09

passed #25489
all
build all 64bit ARM platforms

00:18:52

passed #25490
all
build all PowerPC platforms

00:20:14

passed #25491
all
build all other platforms

00:09:31