Fix incorrectly linted build() command

Created by: vloncar

Description

Recent reformatting of the code changed the build command in build() of vivado_backend.py. The multi-line string is missing spaces between the parameters. The following error happens:

---------error message---------
Sourcing Tcl script 'build_prj.tcl'
expected boolean value but got "Falsecsim"
    while executing
"if {$opt(reset)} {
    open_project -reset ${project_name}_prj
} else {
    open_project ${project_name}_prj
}"
    (file "build_prj.tcl" line 149)
    invoked from within
"source build_prj.tcl"
    ("uplevel" body line 1)
    invoked from within
"uplevel \#0 [list source $arg] "

Hopefully the linter doesn't complain about this.

Type of change

• Bug fix (non-breaking change that fixes an issue)

Tests

The Jenkins tests should prove that this works.

Checklist

• I have installed and run pre-commit on the files I edited or added. -> I actually can't run this and it is Friday evening, so I can't be bothered with fixing my setup.