Deprecation warning due to invalid escape sequences

Deprecation warning due to invalid escape sequences. Using raw strings or escaping them again helps in resolving this. Check https://github.com/asottile/pyupgrade/ for automatic fix of this.

```
find . -iname '*.py' | grep -Ev 'rdf4|tool|doc' | xargs -P4 -I{} python3.8 -Wall -m py_compile {}
./odo/backends/bcolz.py:71: DeprecationWarning: invalid escape sequence \.
@resource.register('.*\.bcolz/?')
./odo/backends/sql.py:318: DeprecationWarning: invalid escape sequence \s
"""Creates a cached sqlalchemy engine.
./odo/backends/sql.py:701: DeprecationWarning: invalid escape sequence \w
pattern = 'hive://((?P[a-zA-Z_]\w*)@)?(?P[\w.]+)(:(?P\d*))?(/(?P\w*))?'
./odo/backends/hdfs.py:514: DeprecationWarning: invalid escape sequence \w
hdfs_pattern = '(((?P[a-zA-Z]\w*)@)?(?P[\w.-]*)?(:(?P\d+))?:)?(?P[/\w.*-]+)'
./odo/backends/text.py:71: DeprecationWarning: invalid escape sequence \.
@resource.register('.+\.(txt|log)(.gz)?')
./odo/backends/aws.py:155: DeprecationWarning: invalid escape sequence \.
@resource.register('s3://.*\.csv(\.gz)?', priority=18)
./odo/backends/aws.py:160: DeprecationWarning: invalid escape sequence \*
@resource.register('s3://.*\*.csv(\.gz)?', priority=19)
./odo/backends/aws.py:182: DeprecationWarning: invalid escape sequence \.
@resource.register('s3://.*\.txt(\.gz)?', priority=18)
./odo/backends/aws.py:187: DeprecationWarning: invalid escape sequence \.
@resource.register('s3://.*\.json(\.gz)?', priority=18)
./odo/backends/csv.py:340: DeprecationWarning: invalid escape sequence \s
elif (all(re.match('^\s*\D\w*\s*$', n) for n in found_names) and
./odo/backends/csv.py:400: DeprecationWarning: invalid escape sequence \.
@resource.register('.+\.(csv|tsv|ssv|data|dat)(\.gz|\.bz2?)?')
./odo/backends/csv.py:405: DeprecationWarning: invalid escape sequence \*
@resource.register('.*\*.+', priority=12)
./odo/backends/ssh.py:89: DeprecationWarning: invalid escape sequence \w
ssh_pattern = '((?P[a-zA-Z]\w*)@)?(?P[\w.-]*)(:(?P\d+))?:(?P[/\w.*-]+)'
./odo/backends/sas.py:16: DeprecationWarning: invalid escape sequence \.
@resource.register('.+\.(sas7bdat)')
./odo/backends/json.py:213: DeprecationWarning: invalid escape sequence \.
@resource.register('json://.*\.json(\.gz)?', priority=11)
./odo/backends/json.py:220: DeprecationWarning: invalid escape sequence \.
@resource.register('.*\.jsonlines(\.gz)?', priority=11)
./odo/backends/json.py:221: DeprecationWarning: invalid escape sequence \.
@resource.register('jsonlines://.*\.json(\.gz)?', priority=11)
./odo/backends/json.py:228: DeprecationWarning: invalid escape sequence \.
@resource.register('.*\.json(\.gz)?')
./odo/resource.py:14: DeprecationWarning: invalid escape sequence \.
""" Refer to data by strings
./odo/directory.py:53: DeprecationWarning: invalid escape sequence \*
@resource.register('.+' + re_path_sep + '\*\..+', priority=15)
./odo/regex.py:29: DeprecationWarning: invalid escape sequence \d
"""
./versioneer.py:467: DeprecationWarning: invalid escape sequence \s
LONG_VERSION_PY['git'] = '''
```