build(deps): bump raiden-contracts in /requirements

Bumps [raiden-contracts](https://github.com/raiden-network/raiden-contracts) from 0.40.3 to 0.50.1.
- [Release notes](https://github.com/raiden-network/raiden-contracts/releases)
- [Changelog](https://github.com/raiden-network/raiden-contracts/blob/master/CHANGELOG.md)
- [Commits](raiden-network/raiden-contracts@v0.40.3...v0.50.1)

---
updated-dependencies:
- dependency-name: raiden-contracts
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements/requirements-ci.txt

@@ -623,7 +623,7 @@ pyyaml==5.4
     #   matrix-synapse
 raiden-api-client==1.1.1
     # via -r requirements-dev.txt
-raiden-contracts==0.40.3
+raiden-contracts==0.50.1
     # via -r requirements-dev.txt
 raiden-webui==1.2.1
     # via -r requirements-dev.txt

requirements/requirements-dev.txt

@@ -527,7 +527,7 @@ pyyaml==5.4
     # via matrix-synapse
 raiden-api-client==1.1.1
     # via -r requirements-dev.in
-raiden-contracts==0.40.3
+raiden-contracts==0.50.1
     # via -r requirements.txt
 raiden-webui==1.2.1
     # via -r requirements.txt

requirements/requirements.in

@@ -26,7 +26,7 @@ packaging
 psutil
 pysha3
 toml
-raiden-contracts>=0.40.0,<0.41.0
+raiden-contracts>=0.40.0,<0.51.0
 raiden-webui
 requests
 structlog

requirements/requirements.txt

@@ -232,7 +232,7 @@ pysha3==1.0.2
     # via -r requirements.in
 pytz==2019.1
     # via flask-restful
-raiden-contracts==0.40.3
+raiden-contracts==0.50.1
     # via -r requirements.in
 raiden-webui==1.2.1
     # via -r requirements.in