Update dependencies (nightly-2021-03-01)

[viper-admin]

• Update rustc version to nightly-2021-03-01.
• Manualy update outdated dependencies (see the list below).
• Manualy run cargo update.

List of direct outdated dependencies:

$ cargo outdated --root-deps-only --workspace

analysis
================
Name            Project  Compat  Latest  Kind         Platform
----            -------  ------  ------  ----         --------
compiletest_rs  0.5.0    ---     0.6.0   Development  ---
serde_json      1.0.61   1.0.64  1.0.64  Normal       ---

prusti
================
Name        Project  Compat  Latest  Kind    Platform
----        -------  ------  ------  ----    --------
env_logger  0.8.2    0.8.3   0.8.3   Normal  ---

prusti-common
================
Name    Project  Compat  Latest  Kind    Platform
----    -------  ------  ------  ----    --------
config  0.9.3    ---     0.10.1  Normal  ---

viper
================
Name        Project  Compat  Latest  Kind         Platform
----        -------  ------  ------  ----         --------
env_logger  0.8.2    0.8.3   0.8.3   Development  ---
jni         0.17.0   ---     0.19.0  Normal       ---

viper-sys
================
Name        Project  Compat  Latest  Kind    Platform
----        -------  ------  ------  ----    --------
env_logger  0.8.2    0.8.3   0.8.3   Normal  ---
jni         0.17.0   ---     0.19.0  Normal  ---
ureq        1.5.2    1.5.4   2.0.2   Build   ---

jni-gen
================
Name  Project  Compat  Latest  Kind    Platform
----  -------  ------  ------  ----    --------
jni   0.17.0   ---     0.19.0  Normal  ---

prusti-contracts
================
Name      Project  Compat  Latest  Kind         Platform
----      -------  ------  ------  ----         --------
trybuild  1.0.40   1.0.41  1.0.41  Development  ---

prusti-contracts-impl
================
Name   Project  Compat  Latest  Kind    Platform
----   -------  ------  ------  ----    --------
quote  1.0.8    1.0.9   1.0.9   Normal  ---

prusti-specs
================
Name        Project  Compat  Latest  Kind    Platform
----        -------  ------  ------  ----    --------
quote       1.0.8    1.0.9   1.0.9   Normal  ---
serde_json  1.0.61   1.0.64  1.0.64  Normal  ---

prusti-interface
================
Name    Project  Compat  Latest  Kind    Platform
----    -------  ------  ------  ----    --------
config  0.9.3    ---     0.10.1  Normal  ---

prusti-server
================
Name        Project  Compat  Latest  Kind    Platform
----        -------  ------  ------  ----    --------
bincode     1.3.1    1.3.2   1.3.2   Normal  ---
env_logger  0.8.2    0.8.3   0.8.3   Normal  ---
futures     0.1.29   0.1.31  0.3.13  Normal  ---
reqwest     0.9.24   ---     0.11.1  Normal  ---
tokio       0.1.22   ---     1.2.0   Normal  ---
warp        0.1.23   ---     0.3.0   Normal  ---

prusti-tests
================
Name            Project  Compat  Latest  Kind         Platform
----            -------  ------  ------  ----         --------
compiletest_rs  0.5.0    ---     0.6.0   Development  ---

prusti-launch
================
Name   Project  Compat  Latest  Kind    Platform
----   -------  ------  ------  ----    --------
ctrlc  3.1.7    3.1.8   3.1.8   Normal  ---
nix    0.19.1   ---     0.20.0  Normal  cfg(unix)

test-crates
================
Name        Project  Compat  Latest  Kind    Platform
----        -------  ------  ------  ----    --------
env_logger  0.8.2    0.8.3   0.8.3   Normal  ---
rustwide    0.11.0   0.11.1  0.12.0  Normal  ---

systest
================
Name        Project  Compat  Latest  Kind    Platform
----        -------  ------  ------  ----    --------
env_logger  0.8.2    0.8.3   0.8.3   Build   ---
jni         0.17.0   ---     0.19.0  Normal  ---
ureq        1.5.2    1.5.4   2.0.2   Build   ---

@fpoli could you take care of this?

[fpoli]

Updating dependencies is blocked by #415