You can configure a system to make use of this repository, thus:
$ sudo tee /etc/apt/sources.list.d/salsa-freexian-code-pyxian-8993685903.sources >/dev/null <<EOF
Types: deb
URIs: https://gitlab.com/freexian/code/pyxian/-/jobs/8993685903/artifacts/raw/aptly
Suites: stable
Components: main
Signed-By:
 -----BEGIN PGP PUBLIC KEY BLOCK-----
 .
 mDMEYw+BMBYJKwYBBAHaRw8BAQdAnT0Mfqt9MOUZBWdC4VtvZD2v2CT1pOUanuOs
 p+lnPa20OVB5eGlhbiBDSSBBUFQgUmVwbyA8Y29sbGFib3JhdG9ycytweXhpYW4t
 Y2lAZnJlZXhpYW4uY29tPoiWBBMWCgA+FiEEEJblcGziPstZmAptMOE5IrdwZSkF
 AmMPgTACGwMFCRLMAwAFCwkIBwMFFQoJCAsFFgIDAQACHgECF4AACgkQMOE5Irdw
 ZSneyAD/RBX+1sejd3N06URtcVlJiclVCu1UyI8ubHDtQaEaEswA/1XV4jPOK52q
 lfL4zlhujrCIme2UfDx5sFEMqd2slzsM
 =LuoQ
 -----END PGP PUBLIC KEY BLOCK-----
EOF

Alternatively, using the old one-line format, thus:
$ wget -O - https://gitlab.com/freexian/code/pyxian/-/jobs/8993685903/artifacts/raw/aptly/public-key.asc | sudo tee /etc/apt/keyrings/salsa-freexian-code-pyxian-8993685903.asc >/dev/null
$ sudo tee /etc/apt/sources.list.d/salsa-freexian-code-pyxian-8993685903.list >/dev/null <<EOF
deb [signed-by=/etc/apt/keyrings/salsa-freexian-code-pyxian-8993685903.asc] https://gitlab.com/freexian/code/pyxian/-/jobs/8993685903/artifacts/raw/aptly stable main
# deb-src [signed-by=/etc/apt/keyrings/salsa-freexian-code-pyxian-8993685903.asc] https://gitlab.com/freexian/code/pyxian/-/jobs/8993685903/artifacts/raw/aptly stable main
EOF

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