fix: update container/blade usage

[fdalcin]

Depends on pressbooks/pressbooks#2907

[codecov]

Codecov Report

Merging #138 (729c300) into dev (29cf086) will decrease coverage by 0.15%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##                dev     #138      +/-   ##
============================================
- Coverage     78.67%   78.51%   -0.16%     
  Complexity      324      324              
============================================
  Files             9        9              
  Lines          1116     1108       -8     
============================================
- Hits            878      870       -8     
  Misses          238      238              

Impacted Files	Coverage Δ
inc/class-admin.php	82.01% <100.00%> (-0.24%)	⬇️
inc/class-tool.php	74.21% <100.00%> (-0.15%)	⬇️
.../modules/export/thincc/class-commoncartridge12.php	89.22% <100.00%> (ø)
inc/namespace.php	95.45% <100.00%> (-0.20%)	⬇️

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